Which element would have properties most like helium (He)?
A. Ar
B. Hg
C. H
D. O
Answer: A. Ar
Explanation: not anything else besides Ar
The lens labelled (B) has radius 16.5cm on the curved side. Using the shape of the lens to assign the sign of the radius, calculate the focal length of the lens. Give your answer with the correct positive or negative sign using the usual convention for lenses.
Answer:
convex f = 33 cm
concave f = -33 cm
Explanation:
In geometric optics the focal length of a lens is given by
[tex]\frac{1}{f} = ( n-1) \ (\frac{1}{R_2} - \frac{1}{R_1} )[/tex]
where n is the refractive index of the medium, R₁ and R₂ are the focal lengths on each side of the lens.
In this case one of the sides is flat so its focal length is infinite, if the lens is convex the focal length is positive, convergent lens and if it is concave the focal length is negative, divergent lens.
[tex]\frac{1}{f} = (n-1) \ \frac{1}{R}[/tex]
the refractive index of the glass is n = 1.5
let's calculate
1 / f = (1.5 -1) 1 / 16.5
1 / f = 0.03030
f = 33 cm
convex f = 33 cm
concave f = -33 cm
Select the correct answer.
A car moves with an average speed of 45 miles/hour. How long does the car take to travel 90 miles?
OA.
2 minutes
OB.
2 hours
O c.
45 minutes
OD.
45 hours
O E.
90 minutes
Reset
Next
Answer:
B. 2 hours
Explanation:
45 miles an hour times 2 is 90 miles in 2 hours
Answer:
B. 2 Hours
Explanation:
If your going at a constant speed of 45 miles per hour then, it will take two hours because 45x2 is 90. and if you divided 90 and 45, you will get 2.
a car drives 24 meters to the left in three seconds what is the velocity of the car?
Answer:
8 m/s to the left.
Explanation:
Applying,
V = d/t...................... Equation 1
Where V = Velocity of the car, d = distance, t = time
From the question,
Given: d = 24 meters, t = 3 seconds
Substitute these values into equation 1
V = 24/3
V = 8 m/s to the left.
Hence the velocity of the car is 8 m/s to the left.
Gold-198 is a radioactive isotope, and it has a half-life of about 2.5 days.
You have 100 grams of Gold-198. How many grams remain after 20 days?
3.125 grams
1.5625 grams
0.78125 grams
0.390625 grams
Answer: 0.390625 grams
Explanation:
A half-life of an element is the amount of time that it takes for half the mass of the element to decay.
Gold-198 having a half-life of 2.5 days therefore means that every 2.5 days, the mass is cut in half.
If there are 20 days, find out how many half-life periods there are:
= 20 / 2.5
= 8 periods
The half life is:
= Original mass * 0.5^number of half-life periods
= 100 * 0.5⁸
= 0.390625 grams
What are the biotic factors in this image?
Someone help thank you!!
Perhaps the greatest of the Greek astronomers, Hipparchus compiled the first catalog of stars, 49) accurately measured their positions, and defined the basic system of stellar brightnesses which we now call the magnitude system. A particular star in his catalogue has an apparent magnitude of 4 and an absolute -12. Determine the distance to the star.
Answer:
Explanation:
it would be 3 because ju divide 12 by 4
A current 2a flows in a circuit fir 2 minutes. Calculate the charge generated in a circuit
Answer:
the charge generated in the circuit is 240 C.
Explanation:
Given;
current flowing in the circuit, I = 2A
time of current flow, t = 2 minutes = 2 x 60s = 120 s
The current flowing through a given circuit is defined as the quantity of charge flowing through the circuit in a given time.
[tex]I = \frac{Q}{t} \\\\Q = I t[/tex]
where;
Q is the charge flowing in the circuit
Q = 2 x 120
Q = 240 C
Therefore, the charge generated in the circuit is 240 C.
Please help ASAP with questions
a person is sitting on the last bench can see clearly see things written on book but cannot see them distinctly on board. what types of lens is this concave or convex
Answer:
I think concave
Explanation:
3) A 30 kg child slides freely across a "Slip and Slide" on LEVEL GROUND. While the child slides, the force applied to keep them sliding is 0 N. The coefficient of kinetic friction is 0.02. What is the acceleration experienced by the child?
Answer:
a = 0.1962 m/s^2
Explanation:
The magnitude of kinetic friction exerted is given by
[tex]F_k=\mu_kN[/tex]
Where, μ_k= coefficient of kinetic friction= 0.02 and N = reaction force = mg
Where m= mass = 30 Kg and, g is acceleration due to gravity =9.81 m/s^2
F_k=0.02×30×9.81 =5.886 N
Now, since, there is no applied force this kinetic friction force will cause acceleration of the child
⇒ ma = F_k
here, a is the acceleration
⇒30a = 5.886
⇒ a = 0.1962 m/s^2
Suppose that an electron and a positron collide head-on. Both have kinetic energy of 1.20 MeV and rest energy of 0.511 MeV. They produce two photons, which by conservation of momentum must have equal energy and move in opposite directions. What is the energy Ephoton of one of these photons
Answer:
E = 1.711 MeV
Explanation:
From the law of the conservation of energy:
[tex]K.E_{e}+K.E_p + E_{e}+E_{p} = 2 E[/tex]
where,
[tex]K.E_e=K.Ep=[/tex] the kinetic energy of positron and electron = 1.2 MeV
[tex]E_e=E_p =[/tex] Rest energy of the electron and the positron = 0.511 MeV
E = Energy of Photon = ?
Therefore,
[tex]1.2\ MeV + 1.2\ MeV + 0.511\ MeV + 0.511\ MeV = 2E\\\\E = \frac{3.422\ MeV}{2}\\\\[/tex]
E = 1.711 MeV
A spinning disc with a mass of 2.5kg and a radius of 0.80m is rotating with an angular velocity of 1.5 rad/s. A ball of clay with unknown mass is dropped onto the disk and sticks to the very edge causing the angular velocity of the disk to slow to 1.13 rad/s. What is the mass of the ball of clay
Answer:
M = 1.90 Kg
Explanation:
Given data: mass = 2.5 Kg
radius R = 0.8 m
angular velocity ω = 1.5 rad/s
Angular momentum L =0.5×Iω^2
Where, I is the moment of inertia of the spinning disc.
I = 0.5MR^2
I = 0.5×2.5×0.8^2
I = 0.8 Kg/m^2
Then L = 0.5×0.8×1.5^2 = 0.8×2.25 = 0.9 Kg-m^2/sec
Let unknown mass be M
New mass of disc = (2.5+M) Kg, R = 0.8 m
New I = 0.5(2.5+M)(0.8)^2
Since, angular momentum is conserved
Angular momentum before = angular momentum after
0.5×0.5(2.5+M)(0.8)^2×(1.13)^2 = 0.9
Solving for M we get
0.204304(2.5+M)=0.9
M = 1.90 Kg
The first law of thermodynamics (which states that energy is conserved) does not specify the direction in which thermodynamic processes in nature can spontaneously occur.
a. True
b. False
Answer:
a. True
Explanation:
The law of conservation of Energy states that energy cannot be destroyed but can only be converted or transformed from one form to another. Therefore, the sum of the initial kinetic energy and potential energy is equal to the sum of the final kinetic energy and potential energy.
Mathematically, it is given by the formula;
Ki + Ui = Kf + Uf .......equation 1
Where;
Ki and Kf are the initial and final kinetic energy respectively.
Ui and Uf are the initial and final potential energy respectively.
The First Law of Thermodynamics is another way to describe the Law of Conservation of Energy. Typically, the First Law of Thermodynamics states that the change of internal energy of a system is equal to the sum of external work and heat spent on the system.
Mathematically, the First Law of Thermodynamics is given by the formula;
ΔU = Q − W
Where;
ΔU represents the change in internal energy of a system.
Q represents the net heat transfer in and out of the system.
W represents the sum of work (net work) done on or by the system.
Hence, the direction in which any thermodynamic process in nature can spontaneously occur isn't stated by the First Law of Thermodynamics.
a football player starts from rest and speeds up to a final velocity of 12 m/s. the speeding up takes a total of 6 seconds. what is the football players acceleration
Answer:
2 m/s²
Explanation:
From the question given above, the following data were obtained:
Initial velocity (u) = 0 m/s
Final velocity (v) = 12 m/s
Time (t) = 6 s
Acceleration (a) =?
The acceleration of the player can be obtained as follow:
v = u + at
12 = 0 + (a × 6)
12 = 6a
Divide both side by 6
a = 12 / 6
a = 2 m/s²
Thus, the acceleration of the player is 2 m/s²
he electric field is dependent on the distance between the plates. false: The voltage of a connected charged capacitor decreases when the plate area is increased. false: The voltage of a disconnected charged capacitor increases when the plates are brought closer together.
Answer:
False.
Explanation:
The voltage of a disconnected charged capacitor decreases when the plates are brought closer together because the capacitance is inversely proportional to the area. If the area between plates decreases, its capacitance increases and vice versa. There is direct relationship between voltage of a disconnected charged capacitor and plates. If the distance between plates decreases, the voltage of a disconnected charged capacitor is also decreases while on the other hand, if the distance between plates increases, the voltage of a disconnected charged capacitor is also increases.
Which of the following is NOT a reason why humans sleep?
Sleep helps to restore and repair brain tissue.
Sleep restores and rebuilds memories.
Sleep provides a psychic safety valve to discharge unacceptable feelings.
During sleep, growth hormone is released, especially in children.
Answer and Explanation:
The answer is the second answer choice. This is because we humans can rebuild or build memories during the day, it doesn't have to happen via sleep.
The first answer choice IS a reason because you aren't working your brain as hard, so your brain has time to heal. A mouse study suggests that sleep helps restore the brain by flushing out toxins that build up during waking hours.
The third answer choice IS a reason because of the idea of Wish Fulfillment: Sigmund Freud suggested that dreams provide a psychic safety valve to discharge unacceptable feelings. The dream's manifest (apparent) content may also have symbolic meanings (latent content) that signify our unacceptable feelings.
The forth answer choice IS a reason because of the idea of Cognitive Development: Some researchers argue that we dream as a part of brain maturation and cognitive development.
#teamtrees #PAW (Plant And Water)
An observer views four identical objects that are traveling at speeds close to
the speed of light. Can their lengths be used to rank the objects according to
their speeds?
Answer:
D
Explanation:
yes. The shortest object is traveling the fastest.
No,their lengths be used to rank the objects according to their speeds. Because the length of the object is depended on the frame of reference of the observer. Option A is correct.
What is frame of reference?A frame of reference is a mathematical and physical coordinate system whose origin, direction, and scale are given by a collection of reference points.
Because the length of each item is determined by the observer's frame of reference, If an observer is stationary yet traveling at near light speed, he will feel length contraction.
Otherwise, the length of the items should not alter for everyday pace.A spectator sees four identical objects flying at almost the speed of light.
No,their lengths be used to rank the objects according to their speeds. Because the length of the object is depended on the frame of reference of the observer.
Hence,option A is correct.
To learn more about the frame of reference to refer to the link;
https://brainly.com/question/12222532
#SPJ2
10 A particle in circular motion performs 30 oscillations in 6
seconds. Its angular velocity is?
Explanation:
Let omega = angular velocity (in rad/s). Then
omega = (# of oscillations)/(6 s)
= (30 osc)/(6 s) = 5 osc/s
We need to convert this to rad/s:
omega = (5 osc/s)(2π rad/osc)
= 10π rad/s
= 31.4 rad/s
A 7.5 cm tall Aragorn action figure is placed 12.4 cm in front of a double convex lens. If the image of Aragorn is located 7.5 from the lens, what is the focal length of the lens?
Answer:
f = 4.67 cm
Explanation:
Here, we can use the thin lens formula, as follows:
[tex]\frac{1}{f}= \frac{1}{p}+ \frac{1}{q}\\\\[/tex]
where,
f = focal length of lens = ?
p = distance of object from lens = 12.4 cm
q = distance of image from lens = 7.5 cm
Therefore,
[tex]\frac{1}{f} =\frac{1}{12.4\ cm} +\frac{1}{7.5\ cm}\\\\\frac{1}{f} = \frac{1}{4.67\ cm}[/tex]
f = 4.67 cm
A golf club hits a 0.0459 kg golf ball at rest; the club is in contact with the ball for 0.00138 s. Afterwards the ball leaves at 63.9 m/s. How much force acted on the ball? (Unit = N)
Answer: 2120 N is correct
Explanation: correct answer for acellus
What are three ways a driver can cause a car to accelerate?
A. Turn the key in the ignition while the car is stopped.
B. Turn the steering wheel while the car is moving.
C. Press the gas pedal while the car is stopped.
D. Press the brake pedal while the car is moving.
Answer:
B,C,D
Explanation:
Ap3X
A child is holding a wagon from rolling straight back down in a driveway that inclined at 20 degree horizontal. if the wagon weigh 150n with what force must the child pull on the handle if the handle is parallel to the incline?
Answer:
F = 51.3°
Explanation:
The component of weight parallel to the inclined plane must be responsible for the rolling back motion of the car. Hence, the force required to be applied by the child must also be equal to that component of weight:
[tex]F = Parallel\ Component\ of\ Weight\ of\ Wagon= WSin\theta\\[/tex]
where,
W = Weight of Wagon = 150 N
θ = Angle of Inclinition = 20°
Therefore,
[tex]F = (150\ N)Sin\ 20^o[/tex]
F = 51.3°
You are studying a population of flowering plants for several years. When you present your research findings you make the statement that, "Increased allocation of resources to reproduction relative to growth diminished future fecundity." Which of the following graph descriptions could accurately present your data?
a) With seeds in the current year on the y-axis and seeds in the previous year on the x-axis, you would see a line that increased from left to right
b) With survivorship on the y-axis and number of seeds produced on the x-axis, you would see a line that decreased left to right.
c) With leaf area on the y-axis and number of seeds produced on the x-axis, you would see a line that increased left to right
d) With survivorship on the y-axis and number of seeds produced on the x-axis, you would see a line that increased left to right.
e) With seeds in the current year on the y-axis and seeds in the previous year on the x-axis, you would see a line that decreased from left to right
Answer:
Option A
Explanation:
The graph for this problem must depict the following ""Increased allocation of resources to reproduction relative to growth diminished future fecundity."
Hence, the survivor ship must be on the Y axis and the resources on the X axis.
Here the resources include the number of seeds produced.
hence, the higher is the number of seeds (resource), the lower is the survivorship (future fecundity)
Hence, option A is correct
A train sounds its whistle at a constant frequency as it passes by the platform. Compared to the sound emitted by the whistle, the sound that people on the platform hear as the train moves away has a frequency that is ...
-higher
-the same
-lower
-exactly half
Answer: Higher.
Explanation: The doppler effect essentially. "The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding."
A 400 kg satellite is in a circular orbit at an altitude of 500 km above the Earth's surface. Because of air friction, the satellite eventually falls to the Earth's surface, where it hits the ground with a speed of 1.60 km/s. How much energy was transformed into internal energy by means of air friction
Answer:
E = 1.45 x 10⁹ J = 1.45 GJ
Explanation:
According to the law of conservation of energy:
Potential Energy Lost by Satellite = Kinetic Energy + Internal Energy
[tex]mgh = \frac{1}{2} mv^2 + E\\\\E = mgh - \frac{1}{2} mv^2[/tex]
where,
E = Internal Energy = ?
m = mass = 400 kg
g = acceleration due to gravity = 9.81 m/s²
h = height = 500 km = 500000 m
v = speed on ground = 1.6 km/s = 1600 m/s
Therefore,
[tex]E = (400\ kg)(9.81\ m/s^2)(500000\ m)-\frac{1}{2} (400\ kg)(1600\ m/s)^2\\E = 1.962\ x\ 10^9\ J - 0.512\ x\ 10^9\ J[/tex]
E = 1.45 x 10⁹ J = 1.45 GJ
When an object levitates, the magnetic force causes the object to repel. Without this magnetic force, ________ would pull the object down.
Answer:
gravity
Explanation:
I don't know what the explanations would be
A heater has resistance of 10 ohms. It operates at 120 volts. a. What is the current through the heater?
Answer:
I = 12 A
Explanation:
For this exercise we use the relationship that voltage is proportional to the product of current and resistance
V = I R
I = V / R
let's calculate
I = 120/10
I = 12 A
A 10- kg ball starting from rest rolls down a 5 m tall smooth hill from one person to another person who is standing at the bottom of the hill with a big spring whose constant is 100 N/m. How far does the spring compress in order to stop the ball
Answer: 3.13 m
Explanation:
Given
mas of the ball is m=10 kg
The ball rolls down a vertical distance of 5 m
Spring constant of spring is [tex]k=100\ N/m[/tex]
Here, the potential energy of the ball converted into kinetic energy which in turn converts into elastic potential energy
[tex]\Rightarrow mgh=\frac{1}{2}kx^2\quad [\text{x=compression in the spring}]\\\\\Rightarrow 10\times 9.8\times 5=\frac{1}{2}\cdot 100\cdot x^2\\\Rightarrow x=\sqrt{9.8}\\\Rightarrow x=3.13\ m[/tex]
Thus, the spring compresses by 3.13 m.
What is Hooke's law? what is meant by elastic limit?
please answer me
Answer:
Explanation:
The law is about how object will be deformed when certain amount force is applied. Elastic limit is a point where object will not return its previous shape after being deformed