Question 1

In the absence of heat transfer, and assuming negligible losses and no work, conservation of mechanical energy states that the total mechanical energy of a system is&#10;A) increasing&#10;B) constant&#10;C) decreasing&#10;D) decreasing, then constant

Accepted Answer

Conservation of mechanical energy states that total mechanical energy of a system is constant in the absence of heat transfer, negligible losses and no work. Therefore, the total mechanical energy of the system remains constant.

Question 2

What is the SI unit for elastic energy?&#10;A) Newtons&#10;B) Watts&#10;C) Kelvins&#10;D) Joules

Accepted Answer

The SI unit for elastic energy is Joules (J). Newtons (N) are the unit for force, Watts (W) are the unit for power, and Kelvins (K) are the unit for temperature.

Question 3

Power is a fundamental dimension.

Accepted Answer

Power is not a fundamental dimension; it is derived from the fundamental dimensions of mass, length, and time. Power is the rate at which work is done or energy is transferred, typically measured in watts (joules per second).

Question 4

Power is found by dividing work by what other physical quantity?&#10;A) distance&#10;B) mass&#10;C) force&#10;D) time

Accepted Answer

Power is calculated by dividing the amount of work done by the time it takes to do that work.

Question 5

Which produces the greater change in kinetic energy (assume that all of the work goes into kinetic energy):&#10;A) exerting a 10N force for a distance of 5m&#10;B) exerting a force of 20N over a distance of 2m&#10;C) exerting a 30N force for a distance of 1.5m&#10;D) exerting a force of 40N over a distance of 1m

Accepted Answer

The work done, which equals the change in kinetic energy, is calculated as force multiplied by distance. For option A, the work done is 10N * 5m = 50J, which is greater than the work done in the other options.

Question 6

A stone is dropped from a bridge and allowed to free-fall downward. As it falls a certain distance its gravitational potential energy decreases by 1000J . By how much does the stone's
Kinetic energy increase? (Neglect air resistance).

A) 100J
B) 500J
C) 1000J
D) 2200J

Accepted Answer

According to the law of conservation of energy, the total energy of the system remains constant. Initially, the stone has only gravitational potential energy, and as it falls, this potential energy is converted into kinetic energy. Therefore, the decrease in gravitational potential energy is equal to the increase in kinetic energy. So, the stone's kinetic energy increases by 1000J, which is equal to the decrease in potential energy. Thus, the correct choice is C) 1000J.

Question 7

What is the SI unit for work?&#10;A) Newtons&#10;B) Watts&#10;C) Kelvins&#10;D) Joules

Accepted Answer

The SI unit for work is Joules (J). Work is defined as the product of force and displacement in the direction of the force, and the unit for force in SI is Newton (N) and for displacement is meter (m). Thus, the unit for work can be expressed as N*m or J.

Question 8

The law that simply states that energy is conserved is

Accepted Answer

The first law of thermodynamics, also known as the law of conservation of energy, states that energy cannot be created or destroyed, only transferred or converted from one form to another. This law forms the basis for the field of thermodynamics and is fundamental to the understanding of energy in all its forms. The other laws of thermodynamics deal with things like entropy and the efficiency of energy transfer, but the conservation of energy is the most basic and fundamental principle.

Question 9

In the following equation, what does the x stand for? $\text { elastic energy } = \frac { 1 } { 2 } k x ^ { 2 }$&#10;A) deflection of spring from its unstretched position&#10;B) original length of unstretched spring&#10;C) spring force&#10;D) a generic unknown quantity

Accepted Answer

In the equation for elastic energy, $x$ represents the deflection of the spring from its unstretched (or equilibrium) position. This equation is derived from Hooke's Law, where $x$ is the displacement of the spring from its natural length.

Question 10

A ping pong ball and a bowling ball are moving with the same momentum. Which has the greater kinetic energy?&#10;A) The ping pong ball&#10;B) The bowling ball

Accepted Answer

The kinetic energy (KE) of an object is given by the formula KE = 1/2 mv^2, where m is the mass and v is the velocity of the object. For two objects with the same momentum (p = mv), the object with the smaller mass (like the ping pong ball) must have a higher velocity to have the same momentum as the object with a larger mass (like the bowling ball). Since kinetic energy depends on the square of the velocity, the ping pong ball, with its higher velocity, will have greater kinetic energy than the bowling ball.

Question 11

The change in gravitational potential energy is found by multiplying an object's change in elevation by its&#10;A) mass.&#10;B) weight.&#10;C) density.&#10;D) height.

Accepted Answer

The answer of The change in gravitational potential energy is...

Question 12

In the following equation, what does the k stand for? $\text { elastic energy }=\frac{1}{2} k x^{2}$&#10;&#10;A) kinetic energy&#10;B) spring constant&#10;C) elastic constant&#10;D) momentum

Accepted Answer

The answer of In the following equation, what does the...

Question 13

How much kinetic energy does a 3kg soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward your opponents' goal?&#10;A) 60 Joules&#10;B) -60 Joules&#10;C) 600 Joules&#10;D) -600 Joules

Accepted Answer

The answer of How much kinetic energy does a 3kg...

Question 14

What is the SI unit for kinetic energy?&#10;A) Newtons&#10;B) Watts&#10;C) Kelvins&#10;D) Joules

Accepted Answer

The answer of What is the SI unit for kinetic...

Question 15

Energy is a fundamental dimension.

Accepted Answer

The answer of Energy is a fundamental dimension....

Question 16

Work is found by multiplying force by what other physical quantity?&#10;A) distance&#10;B) mass&#10;C) power&#10;D) time

Accepted Answer

The answer of Work is found by multiplying force by...

Question 17

Thermal energy transfer is called&#10;A) temperature difference.&#10;B) heat difference.&#10;C) temperature flux.&#10;D) heat.

Accepted Answer

The answer of Thermal energy transfer is called&#10;A) temperature difference.&#10;B)...

Question 18

What are the SI units for heat?&#10;A) Kelvins&#10;B) Celsius&#10;C) Joules&#10;D) Watts

Accepted Answer

The answer of What are the SI units for heat?&#10;A)...

Question 19

How much kinetic energy does a soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward a goal?&#10;A) 60 Joules&#10;B) -60 Joules&#10;C) 600 Joules&#10;D) -600 Joules

Accepted Answer

The answer of How much kinetic energy does a soccer...

Question 20

Which of the following requires the most work done by the brakes of a car?

Accepted Answer

The answer of Which of the following requires the most...

Question 21

In general, efficiency is defined as&#10;A) output divided by input.&#10;B) input divided by output.&#10;C) output multiplied by input.&#10;D) output minus input.

Accepted Answer

The answer of In general, efficiency is defined as&#10;A) output...

Question 22

A team is more powerful than an individual because&#10;A) the team can do more work than the individual in the same amount of time.&#10;B) the team can do the same amount of work as the individual, but in less time.&#10;C) the team can do more work than the individual in less time.&#10;D) All of the above.

Accepted Answer

The answer of A team is more powerful than an...

Question 23

The SI unit for power is&#10;A) Watts&#10;B) Joules&#10;C) Newtons&#10;D) Horsepower

Accepted Answer

The answer of The SI unit for power is&#10;A) Watts&#10;B)...

Question 24

The time rate of doing work is called&#10;A) energy&#10;B) power&#10;C) force&#10;D) momentum

Accepted Answer

The answer of The time rate of doing work is...

Question 25

Power can be described as&#10;A) how hard you push.&#10;B) how fast you push.&#10;C) how far you push.&#10;D) how long you push.

Accepted Answer

The answer of Power can be described as&#10;A) how hard...

Deck 13: Energy and Power