formula for calculating a cross sectional area of a cylinder
​

The colliding objects stick together after the collision, or some kinetic energy is lost to the environment.

The question is incomplete but I will discuss the concept of inelastic collision generally.

An inelastic collision is a type of collision in which kinetic energy is not conserved. In other words, in an inelastic collision, some of the kinetic energy of the colliding objects is transformed into other forms of energy, such as heat, sound, or deformation of the objects.

In an inelastic collision, the colliding objects stick together after the collision, or some kinetic energy is lost to the environment. This means that the final kinetic energy of the objects is less than the initial kinetic energy, and that the objects move with a lower velocity after the collision than they did before.

Learn more about inelastic Collison:https://brainly.com/question/29013438

#SPJ1

Answer:

Understanding what occurs at the various tectonic plate boundaries supports our understanding of the past and current movement of rocks at Earth's surface because the movement of the plates is responsible for shaping the planet's surface features, such as mountain ranges, ocean basins, and volcanoes. Different types of plate boundaries produce different geological features and events. For example, convergent plate boundaries, where two plates move towards each other, result in subduction zones, where one plate is forced beneath another, and can cause volcanic activity and earthquakes. Divergent plate boundaries, where two plates move away from each other, can cause seafloor spreading, mid-ocean ridges, and rift valleys. Transform plate boundaries, where two plates move past each other, can cause earthquakes. By studying the processes and features associated with these plate boundaries, scientists can gain insight into how the Earth's surface has changed over time and how it continues to change today.

Explanation:

Answer: 849.15NM/S

P= F'.V' ,

WHERE V' IS THE VELOCITY OF THE PROJECT OF THE OBJECT ON WHICH THE FORCE ACTS . THUS,

P= F'.V. = COSФ

P = (135N) (7.4M/S)COS31° = 849.15NM/S

The motor must deliver a torque of 0.00180 N·m to accelerate the turntable from rest to 3.49 rad/s in 2.20 revolutions.

We can use the rotational kinetic energy equation to find the torque required to accelerate the turntable from rest to a final angular velocity of 3.49 rad/s:

KE = (1/2) I ω^2

where KE is the kinetic energy, I is the moment of inertia of the turntable, and ω is the angular velocity.

The moment of inertia of a uniform disk is I = (1/2) m r^2, where m is the mass of the disk and r is its radius. Plugging in the given values, we get:

I = (1/2) (0.240 kg) (0.305 m/2)^2

I = 0.00216 kg·m^2

We know that the turntable must complete 2.20 revolutions to reach its final angular velocity, which is equivalent to 2π(2.20) = 13.8 radians. We can use the rotational kinematic equation to find the initial angular velocity of the turntable:

ω_f^2 = ω_i^2 + 2αθ

where ω_i is the initial angular velocity, ω_f is the final angular velocity, α is the angular acceleration, and θ is the angular displacement. We can rearrange this equation to solve for ω_i:

ω_i = √(ω_f^2 - 2αθ)

Plugging in the given values, we get:

ω_i = √[(3.49 rad/s)^2 - 2((3.49 rad/s) / (2.20 rev)) (2π(2.20 rev))]

ω_i = 0.565 rad/s

The torque required to accelerate the turntable from rest to 3.49 rad/s is given by:

τ = I α

where τ is the torque and α is the angular acceleration. We can use the rotational kinematic equation to find the angular acceleration:

ω_f = ω_i + αt

where t is the time it takes to reach the final angular velocity. Solving for t, we get:

t = (ω_f - ω_i) / α

Plugging in the given values, we get:

t = (3.49 rad/s - 0.565 rad/s) / ((3.49 rad/s) / (2.20 rev))

t = 3.46 s

Now we can use the equation for angular acceleration to find α:

α = (ω_f - ω_i) / t

Plugging in the given values, we get:

α = (3.49 rad/s - 0.565 rad/s) / 3.46 s

α = 0.832 rad/s^2

Finally, we can find the torque required to accelerate the turntable from rest to 3.49 rad/s:

τ = I α

τ = (0.00216 kg·m^2) (0.832 rad/s^2)

τ = 0.00180 N·m

Therefore, the motor must deliver a torque of 0.00180 N·m to accelerate the turntable from rest to 3.49 rad/s in 2.20 revolutions using rotational kinetic energy.

Learn more about torque below.

https://brainly.com/question/20691242

#SPJ1

Answer:

A turntable must spin at 33.3 rev/min (3.49 rad/s) to play an old fashion vinyl record . How much torque must the motor deliver if the turntable is to reach its angular speed in 2.20 revolutions starting from rest ? The turntable is an uniform disk of diameter 30.5 cm and mass 0.240kg​

Explanation:

The moment of inertia of the disk can be calculated as:

I = (1/2) * m * r^2

where m is the mass of the disk and r is the radius (half of the diameter).

r = 0.305 / 2 = 0.1525 m

I = (1/2) * 0.240 kg * (0.1525 m)^2 = 0.00232 kg·m^2

We know the final angular speed of the disk (ωf) and the number of revolutions it takes to reach that speed (θ), and we can calculate the initial angular speed (ωi) as:

ωf^2 = ωi^2 + 2αθ

where α is the angular acceleration, which is related to the torque (τ) applied to the disk:

α = τ / I

Combining these equations, we get:

ωf^2 = ωi^2 + 2(τ / I)θ

τ = I(ωf^2 - ωi^2) / 2θ

We are given ωf = 3.49 rad/s and θ = 2.20 rev = 13.82 rad (since 1 rev = 2π rad). To find ωi, we can use the formula for the angular speed of a rotating object:

ω = v / r

where v is the linear speed of a point on the disk. For a disk rotating about its center, the linear speed varies with the distance from the center, but the average linear speed is half the linear speed at the rim:

v = (1/2)ωiR

where R is the radius of the disk (equal to half the diameter).

R = 0.305 / 2 = 0.1525 m

v = (1/2)ωi(0.1525 m)

ωi = 2v / R = ωfθ / (2π) = (3.49 rad/s)(13.82 rad) / (2π) = 7.25 rad/s

Now we can substitute the values into the formula for torque:

τ = (0.00232 kg·m^2)(3.49^2 - 7.25^2) / (2 * 13.82 rad) = -0.108 N·m

The negative sign indicates that the torque must be applied in the opposite direction to the initial motion of the disk, which makes sense because the disk is starting from rest and needs to accelerate in the positive direction.

Answer:

38 220

Explanation:

Weight =Mg

W=Mg

W = (3900)(9.8)

W = 38 220

Stress refers to a state of mental or emotional strain resulting from adverse or demanding circumstances. It can also refer to the physical forces that act on an object, causing deformation or strain.

In terms of mental or emotional stress, it can result from a variety of factors such as work-related pressure, financial problems, relationship issues, health concerns, and other life events that require us to adapt and cope with changing circumstances.

Physical stress refers to the force or pressure applied to an object, which can cause it to deform, strain, or break. This type of stress can arise from a variety of sources such as gravity, external forces, or internal forces caused by changes in temperature, pressure, or other physical conditions.

Examples of physical stress include tension in a bridge caused by the weight of traffic passing over it, strain in a metal bar due to changes in temperature, or compression of a spring due to a force applied to it. In all cases, the object is subjected to forces that cause it to deform or change shape, leading to stresses that can impact its strength, durability, and performance.

learn more about emotional stress: https://brainly.com/question/11819849

#SPJ1

The object's initial momentum is 0 kg*m/s.

The go-cart starts from rest, so its initial velocity (u) is zero. The final velocity (v) is 20 m/s. The mass of the go-cart is 400 kg.

The formula for momentum (p) is:

p = m * v

where m is mass and v is velocity.

Using the given values, we can calculate the momentum at the final velocity:

p = 400 kg * 20 m/s = 8000 kg*m/s

However, we are asked for the initial momentum, which we can find using the conservation of momentum principle. Since no external forces act on the go-cart, the total momentum of the system remains constant.

At the initial moment when the go-cart is at rest, its velocity (u) is zero and hence its momentum is also zero. Therefore, the initial momentum of the system is 0 kg*m/s.

What is momentum?

Momentum is a fundamental concept in physics that describes the amount of motion an object has. It is defined as the product of an object's mass and velocity.

To know more about momentum, visit:

https://brainly.com/question/30487676

#SPJ1

Answer:

mass=kg

Explanation:

M=(160)(9.8)

M=1568

Answer:

Explanation:The information that would be most likely needed to make the calculation of the gravitational force between an asteroid and a planet other than Earth are:

The mass of the asteroid (A)

The mass of the planet (C)

The distance between the asteroid and the planet (E)

The constant G-6.67 x 10^-11 Nm²/kg (G)

Therefore, the options that apply are A, C, E, and G.

Answer:

The laws of reflection govern how incident light rays are reflected on reflecting surfaces such as mirrors, smooth metal surfaces, and clear water. The laws of reflection are as follows: The incident ray reflected ray, and normal to the mirror’s surface are all in the same plane. The incidence angle equals the reflection angle.

Explanation:

The acceleration due to gravity on Kepler-22b would be 10.9 m/s^2.

The acceleration due to gravity on a planet can be calculated using the formula:

g = GM/r^2

where G is the gravitational constant, M is the mass of the planet, r is the radius of the planet.

For Kepler-22b, we are given that its mass is 36 times that of Earth, so its mass is:

M = 36M_E

where M_E is the mass of Earth. We are also given that its radius is 2.4 times that of Earth, so its radius is:

r = 2.4R_E

where R_E is the radius of Earth.

Substituting these values into the formula for g, we get:

g = GM/r^2

g = G(36M_E)/(2.4R_E)^2

g = G(36M_E)/(5.76R_E^2)

g = (36/5.76)G(M_E/R_E^2)

g = 6.25G(M_E/R_E^2)

The value of g for Earth is approximately 9.81 m/s^2. Substituting this value for G, M_E, and R_E, we get:

g = 6.25(6.674×10^-11 N·m^2/kg^2)(5.97×10^24 kg)/(6.38×10^6 m)^2

g = 10.9 m/s^2

Therefore, the acceleration due to gravity on Kepler-22b is approximately 10.9 m/s^2.

So the answer is not one of the options given.

More on acceleration due to gravity can be found here: https://brainly.com/question/13860566

#SPJ1

Therefore, the volume of the ore is 0.0069 cubic meters.

Volume is a measure of the amount of space that an object or substance occupies. It is a fundamental physical quantity that describes the three-dimensional size of an object or space. The SI unit of volume is the cubic meter (m³), but other units such as liters, gallons, and cubic centimeters (cm³) are also commonly used. Volume can be calculated for regular shapes, such as cubes or cylinders, using mathematical formulas, but for irregular shapes, more complex methods, such as displacement, may be needed.

Here,

To calculate the volume of the ore, we need to convert all the measurements to the same unit. We can choose to convert everything to meters since that's the base unit for volume (cubic meters).

8.8 dm = 0.88 m (1 dm = 0.1 m)

92.4 mm = 0.0924 m (1 mm = 0.001 m)

0.007 dam = 0.07 m (1 dam = 10 m)

Now we can use the formula for volume of a rectangular block:

Volume = length x width x height

Volume = 0.88 m x 0.0924 m x 0.07 m

Volume = 0.0069 cubic meters

To know more about volume,

https://brainly.com/question/25252629

#SPJ9

Answer:i believe the answer is d: a motion force

Explanation:

A. batteries

Renewable energy sources like solar and wind power are often located in remote areas, far from where the energy is needed. This means that the energy must be transported over long distances to reach the end user, which can result in energy losses due to resistance in transmission lines. To address this issue, energy storage devices like batteries are needed to store excess energy generated by renewable sources during periods of low demand, and then release it when demand is high. However, current battery technology still needs improvement in terms of capacity, efficiency, and cost to make it more widely accessible and practical for large-scale renewable energy storage.

Answer:

the unit of m×g×h×10 is no 3

The internal brain processes required to make sense of the environment and choose the best course of action are the subject of cognitive psychology.

Complex attention, executive function, learning and memory, language, perceptual-motor control, and social cognition are the six major cognitive function domains identified by the DSM-5.

The cognitive approach's main characteristics are: a conviction that psychology should be treated as a pure science and that research methods should be based on science. The main focus is on thinking and related mental functions like language, perception, memory, and forgetting.

To know more about psychology visit:-

https://brainly.com/question/13513890?

#SPJ1

Constraints:

Limited space on the unmanned spacecraft for carrying food supplies.

The food must be durable enough to withstand the harsh conditions of space travel and long-term storage on Mars.

Criteria:

Nutritional value: The food must provide adequate nutrition to support the physical and mental health of astronauts during their mission on Mars.

Taste and variety: The food should be appetizing and varied to help maintain astronauts' morale and well-being during their extended stay on Mars.

Cost-effectiveness: Unmanned spacecraft are generally less expensive to build, launch, and operate than manned spacecraft. This is because they do not require life support systems, crew accommodations, or other specialized equipment needed to sustain human life in space.

Safety: Sending unmanned spacecraft eliminates the risks associated with human spaceflight, such as exposure to radiation, accidents, and medical emergencies.

Scientific research: Unmanned spacecraft can be designed to carry a variety of scientific instruments and sensors to collect data and perform experiments in space, without the limitations of human endurance and safety.

Learn more on NASA here: https://brainly.com/question/26560423

#SPJ1

Answer:

All of the above.

Explanation:  

                    Terms

-  Chlorophyll is the green coloring matter of leaves and plants, essential to the production of carbohydrates by photosynthesis, and occurring in a bluish-black form, C55H72MgN4O5 (chlorophyll a), and a dark-green form, C55H70MgN4O6 (chlorophyll b).

- Photosynthesis is the complex process by which carbon dioxide, water, and certain inorganic salts are converted into carbohydrates by green plants, algae, and certain bacteria, using energy from the sun and chlorophyll.

- Carbon dioxide is a colorless, odorless, incombustible gas, CO2, present in the atmosphere and formed during respiration, usually obtained from coal, coke, or natural gas by combustion, from carbohydrates by fermentation, by reaction with limestone or other carbonates, or naturally from springs: used extensively in industry as dry ice, or carbon dioxide snow, in carbonated beverages, fire extinguishers, etc.

- Water is a transparent, odorless, tasteless liquid, a compound of hydrogen and oxygen, H2O, freezing at 32°F or 0°C and boiling at 212°F or 100°C, that in more or less impure state constitutes rain, oceans, lakes, rivers, etc.: it contains 11.188 percent hydrogen and 88.812 oxygen, by weight.

- Plants cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae. Their distinctive features include primary cell walls containing cellulose, hemiculloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or centrioles, except in the gametes, and a unique method of cell division involving the formation of a cell plate or phragmoplast that separates the new daughter cells.  

- Celluar respiration is the oxidation of organic compounds that occur within cells, producing energy for cellular processes.

- Chemical energy is the net potential energy liberated or absorbed during the course of a chemical reaction.

-------------------------------------------------------------------------------------------------

First: True

The process by which Chlorophyll is able to trap energy from Sun is called Photosynthesis, because this trapped light (Electromagnetic) energy is converted into chemical energy and stored in Glucose synthesized from carbon dioxide and water as per following reaction

6CO2 + 6H2O = -—-Light Energy---> C6H12O6+ 6O2

-------------------------------------------------------------------------------------------------------

Second: True

Plants absorb water (H2O) and carbon dioxide (CO2) from the earth and atmosphere during photosynthesis. Water is oxidized, which means it loses electrons, while carbon dioxide is reduced, which means it gets electrons, inside the plant cell. Water is converted into oxygen and carbon dioxide into glucose as a result.

----------------------------------------------------------------------------------------------------

Third: True

During the photosynthetic process in a plant cell, chloroplast produces sugar by transforming light energy into chemical energy held in glucose. The process of cellular respiration in mitochondria converts sugar into energy that plant cells can use to survive and develop.

----------------------------------------------------------------------------------------------------

Fourth: True

In the light reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. This electron is passed to a modified form of chlorophyll called pheophytin, which passes the electron to a quinonemolecule, allowing the start of a flow of electrons down an electron transport chain that leads to the ultimate reduction of NADP to NADPH. In addition, this creates a proton gradient across the chloroplast membrane; its dissipation is used by ATP synthase for the concomitant synthesis of ATP. The chlorophyll molecule regains the lost electron from a water molecule through a process called photolysis, which releases a dioxygen (O2) molecule. The overall equation for the light-dependent reactions under the conditions of non-cyclic electron flow in green plants is:

2 H2O + 2 NADP+ + 3 ADP + 3 Pi + light → 2 NADPH + 2 H++ 3ATP+ O2

-------------------------------------------------------------------------------------------------------

#SPJ1

Kirchhoff's current law is applied in nodal analysis. There will be 'n-1' simultaneous equations to solve when there are 'n' nodes in a given electrical circuit. 'n-1' must be solved in order to retrieve all of the node voltages.

Hence, we can solve for V1 and V2:

V1=Vi(R2+R3−k)k(1−nR3)−R2−R3.

V2=Vi(k−R2−R3(1+nR2))k(nR3−1)+R2+R3.

Nodal analysis is a fundamental approach used to investigate voltage and current distribution in a circuit and is one of the simulations included in SPICE simulators. This method successfully integrates Kirchhoff's and Ohm's laws into a single matrix equation.

The distinction between mesh and nodal analysis is that nodal analysis uses Kirchhoff's current law to calculate the voltages at each node in an equation. Mesh analysis, on the other hand, is an application of Kirchhoff's voltage law, which is used to calculate current.

Learn more about  nodal analysis,

https://brainly.com/question/26099417

#SPJ1

The required distance to come to a stop now is 30 meters.

To solve this problem, we can use the equation:

v^2 = u^2 + 2as

where:

v is the final velocity (zero in this case)

u is the initial velocity (10 m/s in the first instance and 20 m/s in the second instance)

a is the acceleration (which is constant in this case)

s is the distance traveled (6 m in the first instance and we need to find it for the second instance)

Solving for s, we get:

s = (v^2 - u^2) / (2a)

For the first instance:

u = 10 m/s

v = 0 m/s

s = 6 m

a = (v^2 - u^2) / (2s) = (0 - 10^2) / (2 x 6) = -16.67 m/s^2 (negative sign indicates deceleration)

Now, using the same constant force, we can find the required distance s for the second instance:

u = 20 m/s

a = -16.67 m/s^2

v = 0 m/s (since the car stops)

s = (v^2 - u^2) / (2a) = (0 - 20^2) / (2 x -16.67) = 30 m

Therefore, the required distance to come to a stop now is 30 meters.

learn more about force here

https://brainly.com/question/11556949

#SPJ1

Answer: The angular velocity of a car tire is 1 rad/s.

Definition: Angular velocity is the speed at which the angle between two bodies changes when an object rotates or revolves around an axis. This displacement is depicted in the image by the angle formed by a line on one body and a line on the other.

Answer:

(a) The thrust of the rocket can be found using the formula:

Thrust = (mass flow rate) x (exhaust velocity)

The mass flow rate is the rate at which mass is expelled from the rocket, which is equal to the burn rate times the mass fraction of fuel:

mass flow rate = burn rate x (mass of rocket) x (mass fraction of fuel)

mass flow rate = 200 kg/s x 20,000 kg x 0.8

mass flow rate = 32,000 kg/s

The exhaust velocity is given as 1.80 km/s. Therefore, the thrust of the rocket is:

Thrust = 32,000 kg/s x 1.80 km/s

Thrust = 57,600 kN

(b) The time it takes to exhaust the fuel can be found using the formula:

time = (mass of fuel) / (burn rate)

The mass of fuel is 80% of the initial mass of the rocket:

mass of fuel = 0.8 x 20,000 kg

mass of fuel = 16,000 kg

Therefore, the time it takes to exhaust the fuel is:

time = 16,000 kg / 200 kg/s

time = 80 seconds

(c) The rocket's speed at the end of its engine burn can be found using the rocket equation:

Δv = (exhaust velocity) x ln[(initial mass) / (final mass)]

The final mass is the mass of the rocket after it has burned all of its fuel, which is:

final mass = (mass of rocket) - (mass of fuel)

final mass = 20,000 kg - 16,000 kg

final mass = 4,000 kg

The initial mass is 20,000 kg. Therefore, the change in velocity is:

Δv = 1.80 km/s x ln[(20,000 kg) / (4,000 kg)]

Δv = 1.80 km/s x ln(5)

Δv = 3.89 km/s

Since the rocket was initially at rest, its final speed is equal to the change in velocity:

final speed = 3.89 km/s

Therefore, the rocket's speed at the end of its engine burn is 3.89 km/s.

Answer:

The maximum density of water occurs at around 4° Celsius. The density of ice is less than liquid water, so it floats. Upon freezing, the ice density decreases by about 9%.

Explanation:

thanks for the question

When the gas in a swim freshwater lake allows its density to match that of the water around it, the fish is said to be in water level (Pflugrath et al., 2012). The maximal neutral buoyant depth (MNBD) is a limit below which fish will have become lot of negative if they swim. Your overall dive depth should be roughly being one your neutral buoyancy depth, but not less than ten metres (32ft).

Hence, as a solid item is embedded in a liquid, its volume increases, more fluid weight is displaced, increasing the hydrostatic pressure. The buoyant force is at its greatest when a solid item is fully submerged in a fluid.

The formula B = V g, where and V are indeed the entity's volume and capacity, correspondingly, and g is the velocity brought on by gravity, is used to calculate the buoyancy required for just an object. 1000 kg/m3 is the density of water. Thus, the required force is 1000 kg/m3 times 1 L times 9.81 m/s2 equals 9.81 N.

To know more about Freshwater Lake click here .

brainly.com/question/858802

#SPJ1

The equation = RC, where R is the resistance and C is the capacitance, yields the time constant of the circuit. We obtain the value = RC = (5.5 k)(4.5 F) = 24.75 ms = 0.02475 s by substituting the above variables.

In electronics, a circuit is a completely circular channel through which electricity flows. A current source, conductors, and a load make up a straightforward circuit.

The equation = RC, where R is the resistance and C is the capacitance, yields the time constant of the circuit. Inputting the values provided yields:

τ = RC = (5.5 kΩ)(4.5 µF) = 24.75 ms = 0.02475 s

The voltage drop Vc across the capacitor is equal to the voltage of the battery, i.e., Vc = VB = 180 V.

After a very long time, the voltage across the capacitor is equal to the voltage of the battery, i.e., V = VB = 180 V. Substituting the given values, we get:

Q = CV = (4.5 µF)(180 V) = 810 µC = 8.1 × 10⁻⁴ C

The current I in the circuit is equal to the current in the resistor, which is given by Ohm's law as I = V/R, where V is the voltage of the battery. Substituting the given values, we get:

I = V/R = (180 V)/(5.5 kΩ) = 32.73 mA = 3.273 × 10⁻² A

To find the time t when the current through the resistor is one-third of its maximum value, we can set I = (1/3)(VB/R) and solve for t:

(1/3)(VB/R) = (VB/R)e(-t/τ)

e(-t/τ) = 1/3

-t/τ = ln(1/3)

t = τln(3) ≈ 0.867τ

To know more about capacitance visit:-

https://brainly.com/question/28445252

#SPJ1

Answer: 2.858(m/s)

Explanation: F= mg→ m1= 4.0/9.8 = 0.408(kg)

m2= 8 /9.8 = 0.816(kg)

m1v1 = (m1+m2)v2→ v2= m1v1(m1+m2) = 0.408+3/(0.408+0.816)= 2.8589m/s)

The average force of the racquet on the ball, given that the time the racquet is in contact with the ball is 0.004 seconds, is 261 N

The following data were obtained from the question:

We can easily obtain the average force of the racquet on the ball as follow?

F = m(v - u) / t

F = [0.058 ×(9 - -9)] / 0.004

F = [0.058 ×(9 + 9)] / 0.004

F = [0.058 × 18] / 0.004

F = 1.044 / 0.004

F = 261 N

Thus, we can conclude from the above calculation that the average force on the ball is 261 N

Learn more about force:

https://brainly.com/question/12163222

#SPJ1

Acetic anhydride has two hydrogen bond acceptor atoms and one hydrogen bond donor atom.

It can form two hydrogen bonds with another identical molecule and two hydrogen bonds with water.

  O

    //

H3C-C-O-C-CH3

    \\

     O

Acetic anhydride has two hydrogen bond acceptor atoms

Acetic anhydride can form two hydrogen bonds with another identical molecule and two hydrogen bonds with water

To know more about hydrogen bonds, visit :

https://brainly.com/question/30885458

#SPJ1

Answer:

For most people with Alzheimer's — those who have the late-onset variety — symptoms first appear in their mid-60s or later. When the disease develops before age 65, it's considered early-onset Alzheimer's, which can begin as early as a person's 30s, although this is rare.