Answer: 45 A
Explanation:
Primary only protection 3-phase
I = 3 phase kVA / ( 1.723 * V)
I = 30000 / ( 1.732 * 480 ) = 36.085 A
Table 450.3(B)
Currents of 9A or more column
primary only protection = 125%
Max OCPD pri = 125% of I = 1.25 * 36.085 = 45.11 A
Table 450.3(B) Note 1 does not apply, use next smaller Table 240.6(A)
Next smaller = 45 A
list advantages and disadvantages of surface tension
please i really need this urgently
Advantages of Surface tension are -
It gathers water into a ball.
It permits a distinct boundary layer that is similar to a non-Newtonian liquid.
It enables water to rise into a paintbrush through capillary action.
It permits rain to fall as drops as opposed to a stifling mass.
It enables smooth surfaces to form as concrete and liquid metals solidify.
Disadvantages of Surface tension are -
The behavior of water would alter if surface tension were eliminated, some of these changes being related to surface tension's drawbacks. Washing clothing is one example that is close to home. Detergent is required while washing garments due to the comparatively high surface tension of water. Reduced surface tension enables laundry water to fully permeate the garments for better cleaning as part of the task of laundry detergent. It would take far less detergent to wash clothes if water had a naturally low surface tension.
When you want to create a fine water spray, such as with a lawn sprinkler, surface tension again becomes an issue. Surface tension makes it harder to divide water into tiny droplets. Sprinklers could operate on a hose with less pressure if they were used with water that had a lower surface tension.
What is a surface tension ?
Surface tension is the propensity for liquid surfaces that are at rest to condense into the smallest surface area. Razor blades and insects (like water striders), which have a higher density than water, can float on the surface of the water without even becoming partially buried because to surface tension.
Surface tension at liquid-air contacts originates from the liquid molecules' stronger attraction to one another due to cohesion than to the air molecules (due to adhesion).
There are primarily two mechanisms at work. One causes the liquid to constrict by exerting an inward push on the surface molecules. The second force is tangential and parallel to the liquid's surface. The surface tension is the common name for this tangential force.
Overall, the liquid acts as though an elastic membrane was stretched over its surface. However, this comparison should not be drawn too far because surface tension is a characteristic of liquid-air or liquid-vapor interfaces, but the tension in an elastic membrane depends on how much it is deformed.
Advantages of Surface tension are -
It gathers water into a ball.
It permits a distinct boundary layer that is similar to a non-Newtonian liquid.
It enables water to rise into a paintbrush through capillary action.
It permits rain to fall as drops as opposed to a stifling mass.
It enables smooth surfaces to form as concrete and liquid metals solidify.
Disadvantages of Surface tension are -
The behavior of water would alter if surface tension were eliminated, some of these changes being related to surface tension's drawbacks. Washing clothing is one example that is close to home. Detergent is required while washing garments due to the comparatively high surface tension of water. Reduced surface tension enables laundry water to fully permeate the garments for better cleaning as part of the task of laundry detergent. It would take far less detergent to wash clothes if water had a naturally low surface tension.
When you want to create a fine water spray, such as with a lawn sprinkler, surface tension again becomes an issue. Surface tension makes it harder to divide water into tiny droplets. Sprinklers could operate on a hose with less pressure if they were used with water that had a lower surface tension.
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Bryan slid a glass of O] for Dalton across a counter with a speed of 2.1m/s. Unfortunately, Dalton missed it! If the countertop was 1.1m above the floor a) how long did it take for the glass to hit the floor? b) how far horizontally did the glass travel in the air?
A. The time taken for the glass to hit the floor is 0.5 s
B. The horizontal distance travelled by the glass in the air is 1.1 m
A. How to determine the time
The following data were obtained from the question:
Height (h) = 1.1 mAcceleration due to gravity (g) = 9.8 m/s²Time (t) = ?The time taken to hit the ground can be obtained as follow:
h = ½gt²
1.1 = ½ × 9.8 × t²
1.1 = 4.9 × t²
Divide both side by 4.9
t² = 1.1 / 4.9
Take the square root of both side
t = √(1.1 / 4.9)
t = 0.5 s
Thus, the time taken is 0.5 s
B. How to determine horizontal distance
The horizontal distance can be obatined as follow:
Horizontal speed (u) = 2.1 m/sTime (t) = 0.5 sHorizont distance (s) = ?s = ut
s = 2.1 × 0.5
s = 1.1 m
Thus, the horizontal distance is 1.1 m
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To make peanut butter, a machine grinds peanuts into a paste. Which of the following can be considered as a process of this system?Question 16 options:PeanutsMachine grinds peanutsPeanut butter
A process is an action that involves individual items, not the items themselves.
Answer: Machine grinds peanuts
Grant jumps 1.10 m straight up into the air to slam-dunk a basketball into the net. With what speed did he leave the floor?
Grant jumps 1.10 m straight up into the air to slam-dunk a basketball into the net, the speed from which he would have left the floor would be 4.64 m / s .
What are the three equations of motion?There are three equations of motion given by Newton
v = u + at
S = ut + 1/2 × a × t²
v² - u² = 2 × a × s
As given in the problem grant jumps 1.10 m straight up into the air to slam-dunk a basketball into the net.
By using the third equation of the motion,
v² - u² = 2 × a × s
0 - u² = 2 × -9.81 × 1.10
u = 4.64 m / s
Thus, the speed from which he would have left the floor would be 4.64 m / s .
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if i put my spoon in the microwave what will happen
If you put your spoon in the microwave, nothing will happen to it as long as it has round edges and it is not touching any sides of the microwave.
Putting a spoon in the microwaveSpoons are generally made from stainless steel. Stainless steels are iron and chromium. In some cases, other metals such as nickel are thrown into the mix.
Thus, being made of metals, these stainless steels are good conductors of heat and electricity.
A microwave works by heating foods put into it using electromagnetic radiation in the microwave frequency range. Electromagnetic radiation causes the molecules of food to rotate and produce thermal energy.
If the spoon touches the side of the microwave, sparks may result. Otherwise, it is totally fine because spoons usually have round edges. With rough edges, the waves may be reflected back and forth and create sparks.
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A rock sample has a mass of 6 kg and a volume of 0.002 m3. Calculate the density of this rock sample.
The density of the rock sample is 3000 kg/m³.
Density is an important property of matter because it can be used to determine the weight of an object. For example, if you know the density of a rock sample and its volume, you can calculate its weight by multiplying the density by the volume. Density can also be used to determine the composition of a material. For example, if you know the densities of different materials, you can identify the material of a rock sample by measuring its density.
Density is a measure of how much mass is contained in a given volume.. The calculation of the density of the rock sample:
Density = Mass / Volume
Density = 6 kg / 0.002 m³
Density = 3000 kg/m³
As a result, the rock sample has a density of 3000 kg/m³.
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Timothy wants to know how far his math class is from the orange tree across the street from the school. His feet are ideal feet (meaning they are 1 foot long. 1 foot is 12 inches). Timothy finds that the orange tree is 159 feet from the door of the math classroom. He wants to know that distance in kilometers (km).a. Convert from feet to inches (1 ft =12 in)b. Convert from inches to centimeters (1 in =2.54c. Conver from centimeters to meters (1m = 100cm)d. Convert from meters to kilometers (1km=1000m)
a) 1 foot = 12 inches
159 feet = 159 x 12 = 1908
The distance in inches is 1908 inches
b) 1 inch = 2.54 cm
1908 inches = 1908 x 2.54 = 4846.32
The distance in centimeters is 4846.32 cm
c) 100 cm = 1 m
4846.32 cm = 4846.32/100 = 48.4632
The distance in meters is 48.4632 m
d) 1000m = 1 km
48.4632 m = 48.4632/1000 = 0.0484632
The distance in kilometers is 0.0484632 km
The critical angle for a certain liquid-air surface is 20°. What is the index of refraction of this liquid?
ANSWER
[tex]\begin{equation*} 2.92 \end{equation*}[/tex]EXPLANATION
To find the index of refraction of the liquid, we have to apply the formula for critical angle:
[tex]\theta=\sin^{-1}(\frac{n_r}{n_i})[/tex]where nr = refractive index of air = 1
ni = refractive index of liquid
Hence, by substituting the given values into the equation, we have that the index of refraction of the liquid is:
[tex]\begin{gathered} 20=\sin^{-1}(\frac{1}{n_i}) \\ \sin20=\frac{1}{n_i} \\ n_i=\frac{1}{\sin20} \\ n_i=2.92 \end{gathered}[/tex]That is the answer.
An electric oven has a resistance of 50.0 Ω and a voltage of 220 V. How much current does it draw?
Given
Resistance of the oven, R=50.0 ohm,
Voltage is V=220 V
To find
The current drawn
Explanation
Let the current be I
By Ohm's law,
[tex]V=RI[/tex]Putting the values,
[tex]\begin{gathered} 220=50I \\ \Rightarrow I=4.4A \end{gathered}[/tex]Conclusion
The current drawn is 4.4 A
A 65.0-kg basketball player jumps vertically and leaves the floor with a velocity of 1.80 m/s upward. (a) What impulse does the player experience? (b) What force does the floor exert on the player before the jump? (c) What is the total average force exerted by the floor on the player if the player is in contact with the floor for 0.450 s during the jump?
(a) The impulse experienced by the player is 117 Ns.
(b) The force the floor exert on the player before the jump is 637 N.
(c) The total average force exerted by the floor on the player if the player is in contact with the floor for 0.450 s during the jump is 260 N.
What impulse does the player experience?
The impulse experienced by the player is the change in the momentum of the player.
J = ΔP
J = m(v - u)
where;
m is the mass of the playerv is the final velocity of the player = 0u is the initial velocity of the player = - 1.8 m/s (negative because of upward direction)J = 65 x (0 + 1.8)
J = 117 Ns
The force the floor exert on the player before the jump is calculated as;
F = mg
where;
g is acceleration is due to gravityF = 65 x 9.8
F = 637 N
The total average force exerted by the floor on the player if the player is in contact with the floor for 0.450 s during the jump is calculated as;
F = ma
F = m(v/t)
F = (mv)/t
F = (65 x 1.8) / 0.45
F = 260 N
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Tsunami waves generally carry a mass (m) of 770 kg of water, travel at a velocity (v) of approximately 10 m/s and have a height (h) of 10 m at landfall. The colony structures can withstand a total energy (TE) 135,000 J before catastrophic damage occurs.ANSWER (a) AND (b)(a) Using your answers from #4 and #5 calculate the total energy (TE) of a tsunami wave. TE = KE + PE (b) Using your calculations and the provided data, explain to the colonizing council whether this crash site can be used to start a colony.
ANSWER:
(a)
Potential energy = 75460 J
Kinetic energy = 38500 J
Total energy = 113960 J
(b)
The site can be used to start a colony.
STEP-BY-STEP EXPLANATION:
Given:
Mass (m) = 770 kg
Velocity (v) = 10m/s
Height (h) = 10 m
(a)
We calculate in each case the kinetic and potential energy by means of their formulas
[tex]\begin{gathered} E_k=\frac{1}{2}m\cdot v^2=\frac{1}{2}\cdot770\cdot10^2=38500\text{ J} \\ E_p=m\cdot g\cdot h=770\cdot9.8\cdot10=75460\text{ J} \end{gathered}[/tex]The total energy is the sum of both calculated energies:
[tex]\begin{gathered} E_T=38500+75460 \\ E_T=113960\text{ J} \end{gathered}[/tex](b)
Since the tsunami energy is less than the energy that can destroy the colony, then the site can support a permanent colony.
On a standard day the speed of sound is 345 meters per second. A whistle whose frequency is 725 Hz is movingtoward an observer at a speed of 25.2 meters per second. What is the wavelength of the sound at the observer?(a) 0.367 m(b) 0.441 m(c) 0.511 m(d) 0.623 m
Take into account that this is a situation where the source moves presenting the Doppler effect.
In order to determine the wavelength of the sound generatd by the whistle at the observer, first calculate the frequency at the observer by using the following formula:
[tex]f=\frac{v}{v-v_s}f_s[/tex]where:
f: frequency at the observer = ?
fo: source frequency = 725 Hz
vs: source speed = 25.2 m/s
v: speed of sound = 345 m/s
replace the previous values of the parameters into the fomrula for f:
[tex]\begin{gathered} f=\frac{345m/s}{345m/s-25.2m/s}725Hz \\ f=782.1Hz \end{gathered}[/tex]Next, use the following formula to determine the wavelength of the sound at observer, by using the previous result:
[tex]\lambda=\frac{v}{f_s}=\frac{345m/s}{782.1Hz}=0.441m[/tex]Hence, the wavelength of the sound at the observer is 0.441 m
Newton’s Second Law states “The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.” Explain how your observations in both a and b support this Law.
Newton’s Second Law states “The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.”
What is Newton's second law?Newton's Second Law states that The resultant force acting on an object is proportional to the rate of change of momentum.
Force = mass × acceleration
Assuming the force constant the acceleration is inversely proportional to the mass of the object.
Thus, acceleration is directly proportional to force and inversely proportional to the mass of the body.
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The source of the Sun’s heat and light energy is:A. combustion of helium gas.B. fusion of hydrogen nuclei.C. gravitational pressure.D. burning of fossil fuels.
To find
The source of the Sun’s heat and light energy is:
Explanation
The sun's core is very hot. So under pressure nuclear fusion takes place. Here hydrogen is changed to helium.
Conclusion
The correct option is
B. fusion of hydrogen nuclei.
Two Styrofoam blocks are brought near each other and are observed to repel each other. Each block has the same amount of charge on it. Which statement is true about this situation? A)the charge on each block must be positive B)the charge on each block must be negative C)the blocks are creating magnetic fields from non moving electric charges D)each block has the same kind of charge but we don't' know what kind it is
ANSWER:
D)each block has the same kind of charge but we don't' know what kind it is
STEP-BY-STEP EXPLANATION:
Two charges of the same type always repel each other.
In this case, it is not possible to know what type of load they are, only that they are the same.
Therefore, the correct answer is:
D)each block has the same kind of charge but we don't' know what kind it is
Which of the following circuits can be used to measure the resistance of the heating element, shown as a resistor in the diagrams below?
In order to measure the resistance in the circuit, we need to know the voltage V and the current I in the circuit, this way we can calculate the resistance using the formula:
[tex]R=\frac{V}{I}[/tex]In order to calculate the current, we can use an amperemeter that must be in series with the circuit, this way it will not affect the circuit.
And in order to calculate the voltage, we can use a voltmeter that must be in parallel with the resistance, this way it will not affect the circuit.
The correct option that shows an amperemeter in series and a voltmeter in parallel is the fourth option.
Peter is trying to ignite the hotplate by turning the gas knob. Suppose thatthe minimum moment of couple about the center of the gas knob requiredto ignite the hotplate is 0.3 N m. Calculate the minimum force (F, and F2)that required to exert. Given that the diameter of gas knob is 5 cm.
the minimum force is 6 Newtons
Explanation
A moment of a force, or a torque, is a measure of a force's tendency to cause a body to rotate. The moment depends on both the force, and on the position at which the force acts, it is given by the expression
[tex]M=F\cdot d\text{ }[/tex]where F is the exerted force and d is the distance
Step 1
then, let
[tex]\begin{gathered} M=\text{0}.3\text{ Nm} \\ F=F \\ \text{distance}=\text{ 5 cm= }\frac{5}{100}m=0.05\text{ m} \\ \end{gathered}[/tex]now, replace in the formula
[tex]\begin{gathered} M=F\cdot d\text{ } \\ 0.3\text{ Nm=F}\cdot0.05\text{ m} \\ \text{divide both sides by 0.05 m} \\ \frac{0.3\text{ Nm}}{0.05\text{ m}}\text{=}\frac{\text{F}\cdot0.05\text{ m}}{0.05\text{ m}} \\ 6N=F \end{gathered}[/tex]therefore, the minimum force is 6 Newtons
I hope this helps you
Changes of state occur at segment _____________ and segment_______________.1st blankA-BB-CC-D2nd blank C-DD-EE-F
The change of phase takes place when the amount of heat added is changing the state and the temperature of the system remains constant.
In the given graph, the ice is changed into the water state through segment B-C.
Then the water is changed into a water vapor state in the segment D-E.
Hence, changes of state occur at segment B-C and segment D-E.
How much work does Scott do to push a 74 kg sofa 2.1 m across the floor at a constant speed? The coefficient of kinetic friction between the sofa and the floor is 0.23.
Work does Scott do to push a 74 kg sofa 2.1 m across the floor at a constant speed. The coefficient of kinetic friction between the sofa and the floor is 0.23 is 349 Nm.
given that :
mass = 74 kg
distance d = 2.1 m
coefficient of kinetic friction , μk = 0.23
work done is given as :
w = fd
f = μk m g
f = 0.23 × 74 × 9.8
f = 166 N
therefore ,
work = fd
w = 168 × 2.1
w = 349 Nm
Work does Scott do to push a 74 kg sofa 2.1 m across the floor at a constant speed. The coefficient of kinetic friction between the sofa and the floor is 0.23 is 349 Nm.
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Four wires running through the corners of a square with sides of length 16.166 cm carry equal currents, 3.684 A. Calculate the magnetic field at the center of the square.
For practical reasons, we can consider each side of the square as an infinite wire. This can be seen on the following drawing:
This way, the field on the center will be the sum of the contribution of each wire. We can calculate the contribution of a single wire as:
[tex]B=\frac{\mu_0i}{2\pi d}=\frac{4\pi *10^{-7}*3.684}{2\pi(\frac{16.166*10^{-2}}{2})}=9.115*10^{-6}T[/tex]Then, the total field will be this, multiplied by the number of wires:
[tex]B_t=4*9.115*10^{-6}=36.46\mu T[/tex]Then, the resulting field will be Bt=36.46uT
The position of a particle is F(t) = 4.01²î - 3.0ĵ +2.03 km. (a) What is the velocity of the particle at 0 s and at 1.0 s? (b) What is the average velocity between 0 s and 1.0
The velocity of the particle at 0 s and at 1.0 and the average velocity between 0 s and 1.0
a)[tex]\vec{V}(0)=0 m / s[/tex]
[tex]\vec{V}(1)=(8 \hat{\imath}+6 \hat{k}) m / s[/tex]
b)[tex](4 \hat{\imath}+2 \hat{k}) \mathrm{m} / \mathrm{s}[/tex]
This is further explained below.
What is the average velocity?Generally, the equation for the Position is mathematically given as
F(t) = 4.01²î - 3.0ĵ +2.03 km.
Therefore
[tex]\begin{aligned}&\vec{r}(t)=\left(4 t^2 \hat{l}-3 \hat{\jmath}+2 t^3 \hat{k}\right) m \\&\vec{V}(t)=\frac{d \vec{r}(t)}{d t}=\left(8 t \hat{\imath}+6 t^2 \hat{k}\right) m / s\end{aligned}[/tex]
For A
[tex]\begin{aligned}&\vec{V}(0)=0 m / s \\&\vec{V}(1)=(8 \hat{\imath}+6 \hat{k}) m / s\end{aligned}[/tex]
For B
[tex]\text { Average velocity } &=\frac{\text { Total displacement }}{\text { time interval }} \\[/tex]
[tex]=\frac{\vec{r}(1)-\vec{r}(0)}{1} \\&=4 \hat{\imath}-3 \hat{\jmath}+2 \hat{k}-\left(-3 \hat{\jmath}^{\prime}\right) \\&=(4 \hat{\imath}+2 \hat{k}) \mathrm{m} / \mathrm{s}\end{aligned}[/tex]
In conclusion, The speed of the particle at 0 seconds and at 1.0 seconds, as well as the average speed between 0 seconds and 1.0 seconds
a)[tex]\vec{V}(0)=0 m / s[/tex]
[tex]\vec{V}(1)=(8 \hat{\imath}+6 \hat{k}) m / s[/tex]
b)[tex](4 \hat{\imath}+2 \hat{k}) \mathrm{m} / \mathrm{s}[/tex]
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A quantity of steam (650 g) at 116°C is condensed, and the resulting water is frozen into ice at 0°C. How much heat was removed?answer in:____ kcal
Total heat removed = 473.04 kCal
Explanation:Heat removed to convert the 116°C to 100°C steam
[tex]\begin{gathered} H=mc(\theta_2-\theta_1) \\ \\ H=650(1.996)(116-100) \\ \\ H=20758.4J \end{gathered}[/tex]Heat removed from 100°C of steam to 100°C of water (Latent heat of condensation)
[tex]\begin{gathered} H_c=650\times2257 \\ \\ H_c=1467050J \end{gathered}[/tex]Heat removed from 100°C water to 0°C water
[tex]\begin{gathered} H_w=650\times4.2\times100 \\ \\ H_w=273000J \end{gathered}[/tex]Heat removed from 0°C water to 0°C ice
[tex]\begin{gathered} H_i=mL_f \\ \\ H_i=650(336) \\ \\ H_i=218400J \end{gathered}[/tex]Total heat removed = 20758.4J + 1467050 + 273000 + 218400
Total heat removed = 1979208.4 J
Convert to kilocalorie
Total heat removed = 1979208.4/4184
Total heat removed = 473.04 kCal
You and some friends are duck pin bowling. You’re up and you roll your bowling ball (m = 1.6kg) down the lane. It collided with one pin (0.68kg) on the end in a perfectly elastic one dimensional collision. If the ball was moving at a velocity of 6 m/s just before it hits the pin, what is the velocity of the bowling pin after the collision?
Given:
The mass of the bowling ball is m1 = 1.6 kg
The mass of the pin is m2 = 0.68 kg
The initial velocity of the ball is
[tex]v_i=\text{ 6 m/s}[/tex]Required: Velocity of the bowling pin after the collision.
Explanation:
According to the conservation of momentum, the velocity after the collision will be
[tex]\begin{gathered} m1v_i+m2\times0\text{ =\lparen m1+m2\rparen v}_f \\ v_f=\frac{m1v_i}{m1+m2} \\ =\frac{1.6\times6}{1.6+0.68} \\ =4.21\text{ m/s} \end{gathered}[/tex]Final Answer: The velocity of the bowling pin after the collision is 4.21 m/s
find an equation of the line with y intercept (0,7) and the slope of 1/2
Consider that a general way of writing a line equation is:
y = mx + b
where m is the slope of the line and b is the y coordinate of the y-intercept of the line.
Then, by using the given information:
m = 1/2
b = 7
You have the following equation of line:
y = 1/2*x + 7
Mass/energy equivalence is expressed mathematically in which of the following expressions?
Check each option to see how it relates to different concepts.
Option 1: E=hf
This equation tells the energy carried by an electromagnetic wave with frequency f.
Option 2: E=mc
This equation is not correct, since the left member is measured in units of energy and the right member does not.
Option 3: E=(1/2)mv^2
This equation relates the energy of a moving object with its mass and its velocity. It is known as kinetic energy.
Option 4: E=mc^2
Since c is a constant (the speed of light), this equation relates the energy of an object with its mass.
Therefore, the mass/energy equivalence is expressed mathematically in the equation:
[tex]E=mc^2[/tex]According to Figure 2. the solar radiation Intensity 8.000 years ago was closest towhich of the following?490 watts/m20495 watts/m?O 500 watts/m2O 505 watts/m2
From the given figure, let's determine the solar radiation intensity 8000 years ago.
We can see the solar radiation intensity is represented on the left vertical (left side of the y-axis), while the number of years is represented on the x-axis.
Using the graph, at 8 thousand(8000) years ago, the radiation intensity was closest to 500 watts/m².
T
44) Find the x coordinate of the center of mass of the bricks shown.
We are asked to determine the x-coordinate of the center of mass of the given bricks. To do that, we will use the following formula:
[tex]\bar{x}=\frac{\Sigma x_im_i}{\Sigma m_i}[/tex]Where:
[tex]\begin{gathered} x_i=\text{ x-coordinate of the center of mass of each brick} \\ m_i=\text{ mass of each brick} \end{gathered}[/tex]Since we have three bricks, the formula expands to:
[tex]\bar{x}=\frac{x_1m_1+x_2m_2_{}+x_3m_3}{m_1+m_2+m_3}[/tex]Since we have three bricks with the same characteristics we will assume the three of them have the same mass:
[tex]\bar{x}=\frac{x_1m_{}+x_2m+x_3m_{}}{m_{}+m_{}+m_{}}[/tex]Taking "m" as a common factor and adding like terms in the denominator we get:
[tex]\bar{x}=\frac{m(x_1+x_2+x_3)}{3m}[/tex]Now we cancel out the "m":
[tex]\bar{x}=\frac{x_1+x_2+x_3}{3}[/tex]Now we determine the x-coordinates of each brick. Each brick is a parallelepiped, therefore, the x-coordinate is in the middle. Since each brick measures L, this means that the x-coordinate of the first brick is:
[tex]x_1=\frac{L}{2}[/tex]For the second brick, we have the L/2 of the separation from the first plus the L/2 of its length, therefore:
[tex]x_2=\frac{L}{2}+\frac{L}{2}=L[/tex]Now, for the third brick we have the L/4 of the separation from the second brick plus the L/2 of the separation of the second brick and the first brick and the L/2 of the length of the third brick, therefore:
[tex]x_3=\frac{L}{2}+\frac{L}{4}+\frac{L}{2}=\frac{5L}{4}[/tex]Now we substitute in the formula for the x-coordinate:
[tex]\bar{x}=\frac{(\frac{L}{2})+(L)+(\frac{5L}{4})}{3}[/tex]Adding like terms in the numerator:
[tex]\bar{x}=\frac{\frac{11L}{2}}{3}[/tex]Simplifying:
[tex]\bar{x}=\frac{11L}{6}[/tex]Therefore, the x-coordinate of the center of mass is located at 11L/6 from the origin.
Using the work energy theorem, what is the final velocity of a roller coaster at the bottom of the hill. The coaster has a mass of 839 kg and starts at rest from the top of a hill that is 75 meters tall.
ANSWER
38.34 m/s
EXPLANATION
Given:
• The mass of the coaster, m = 839 kg
,• The initial height of the coaster, h = 75 m
,• The acceleration due to gravity, g = 9.8 m/s²
Find:
• The final velocity of the roller coaster at the bottom of the hill, v.
The roller coaster starts from rest, so at the top of the hill, it only has gravitational potential energy and no kinetic energy. Then, at the bottom of the hill, the roller coaster is in motion, to it has kinetic energy, and, because the difference of height with the reference - which is the bottom of the hill, is zero, it has no potential energy,
By the work-energy theorem, we have the equation,
[tex]KE_i+PE_i+W_{nc}=KE_f+PE_f_{}[/tex]As explained above, the initial kinetic energy is 0 and the final potential energy is also 0. If we assume that there is no friction, air resistance, or other external forces, then the work done by non-conservative forces is also 0,
[tex]PE_i=KE_f[/tex]Replace each kind of energy with the expression to obtain them,
[tex]m\cdot g\cdot h=\frac{1}{2}\cdot m\cdot v^2[/tex]The mass cancels out,
[tex]g\cdot h=\frac{1}{2}\cdot v^2[/tex]Solving for v,
[tex]v=\sqrt[]{2\cdot g\cdot h}[/tex]Replace with the known values and solve,
[tex]v=\sqrt[]{2\cdot9.8m/s^2\cdot75m}=\sqrt[]{1470m^2/s^2}\approx38.34m/s[/tex]Hence, the velocity of the roller coaster at the bottom of the hill is 38.34 m/s, rounded to the nearest hundredth.
A student on skateboard pushes off from the top of small hill with a apees of 2.0m/s, and then geos down the hill with a constant acceleration of 0.5 m/s2
After traveling a distancie 12.0m, how fast is the student going?
The final velocity of the student after travelling 12 m is 4 m/s.
What is the final velocity of the student?
The final velocity of the student is determined by applying the following Kinematic equation.
v² = u² + 2as
where;
u is the initial velocity of the studentv is the final velocity of the studenta is the acceleration of the students is the distance travelled by the studentv² = (2)² + 2(0.5)(12)
v² = 16
v = √16
v = 4 m/s
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A wooden sphere of mass 4.0 kg is completely immersed in water. A pushing force of 20. N is
applied.
21°
20 N
4.2 ms²
19⁰
At the moment shown in the diagram, the sphere is stationary and it experiences an
acceleration upwards and to the right as shown.
Calculate the size of the upwards force due to the water (upthrust) acting on the sphere.
The size of the upwards force due to the water (upthrust) acting on the sphere is 12.64 N.
What is upthrust?
Buoyancy or upthrust, is an upward force exerted by a fluid on an object immersed in the fluid due to the weight of the object
Thus, upthrust is the upward force acting on an object immersed in a liquid.
Fu - Df = F(net_u)
where;
Fu is the upward forceDf is the downward force applied on the objectF(net_u) is the net upward forceFu - F x sin(21) = ma x sin(19)
where;
m is the mass of the wooden spherea is the upward acceleration of the wooden sphereFu - 20 x sin(21) = (4 x 4.2) x sin(19)
Fu - 7.17 = 5.47
Fu = 12.64 N
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