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

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?

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?

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):

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).

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?

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? $\text { elastic energy } = \frac { 1 } { 2 } k x ^ { 2 }$

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?

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

Accepted Answer

The change in gravitational potential energy is calculated by multiplying the object's weight (mass * acceleration due to gravity) by its change in height. Weight is the force due to gravity, which directly influences gravitational potential energy.

Question 12

In the following equation, what does the k stand for? $\text { elastic energy }=\frac{1}{2} k x^{2}$

Accepted Answer

B) The spring constant, denoted by $k$, represents the stiffness of the spring in the equation for elastic potential energy, $\frac{1}{2} k x^{2}$, where $x$ is the displacement of the spring from its equilibrium position.

Question 13

How much kinetic energy does a 3kg soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward your opponents' goal?

Accepted Answer

The kinetic energy (KE) of an object can be calculated using the formula $KE = \frac{1}{2}mv^2$, where $m$ is the mass of the object and $v$ is its velocity. Substituting the given values, $m = 3 \, \text{kg}$ and $v = 20 \, \text{m/s}$, we get $KE = \frac{1}{2} \times 3 \times (20)^2 = \frac{1}{2} \times 3 \times 400 = 1.5 \times 400 = 600 \, \text{Joules}$.

Question 14

What is the SI unit for kinetic energy?

Accepted Answer

The SI unit for kinetic energy is Joules (J). This is because kinetic energy is defined as the energy an object possesses due to its motion, and the unit for energy is Joules.

Question 15

Energy is a fundamental dimension.

Accepted Answer

Energy is not a fundamental dimension itself; it is a derived quantity in physics, typically measured in terms of other fundamental dimensions such as mass, length, and time (e.g., joules in the SI system, where 1 joule = 1 kg·m²/s²). Fundamental dimensions include mass, length, time, electric current, temperature, amount of substance, and luminous intensity.

Question 16

Work is found by multiplying force by what other physical quantity?

Accepted Answer

Work is calculated by multiplying the force applied to an object by the distance over which that force is applied, in the direction of the force.

Question 17

Thermal energy transfer is called

Accepted Answer

Thermal energy transfer is commonly known as heat.

Question 18

What are the SI units for heat?

Accepted Answer

Heat is a form of energy, and the SI unit for energy is the Joule. Kelvins and Celsius are units of temperature, while Watts are units of power.

Question 19

How much kinetic energy does a soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward a goal?

Accepted Answer

The kinetic energy ($KE$) of an object can be calculated using the formula $KE = \frac{1}{2}mv^2$, where $m$ is the mass of the object and $v$ is its velocity. Assuming the mass of the soccer ball is $3 \mathrm{~kg}$ (a typical mass for a soccer ball), and given its velocity is $20 \mathrm{~m/s}$, the kinetic energy would be $KE = \frac{1}{2} \times 3 \mathrm{~kg} \times (20 \mathrm{~m/s})^2 = 600 \mathrm{~Joules}$. Kinetic energy is always positive, as it represents the energy an object possesses due to its motion.

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...

Quiz 13: Energy and Power

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

What is the SI unit for elastic energy?

Power is a fundamental dimension.

Power is found by dividing work by what other physical quantity?

Which produces the greater change in kinetic energy (assume that all of the work goes into kinetic energy) :

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) .

What is the SI unit for work?

The law that simply states that energy is conserved is

In the following equation, what does the x stand for? $\text { elastic energy } = \frac { 1 } { 2 } k x ^ { 2 }$

A ping pong ball and a bowling ball are moving with the same momentum. Which has the greater kinetic energy?

The change in gravitational potential energy is found by multiplying an object's change in elevation by its

In the following equation, what does the k stand for? $\text { elastic energy }=\frac{1}{2} k x^{2}$

How much kinetic energy does a 3kg soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward your opponents' goal?

What is the SI unit for kinetic energy?

Energy is a fundamental dimension.

Work is found by multiplying force by what other physical quantity?

Thermal energy transfer is called

What are the SI units for heat?

How much kinetic energy does a soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward a goal?

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

Quiz 13: Energy and Power

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

What is the SI unit for elastic energy?

Power is a fundamental dimension.

Power is found by dividing work by what other physical quantity?

Which produces the greater change in kinetic energy (assume that all of the work goes into kinetic energy) :

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) .

What is the SI unit for work?

The law that simply states that energy is conserved is

In the following equation, what does the x stand for? elastic energy =12kx2\text { elastic energy } = \frac { 1 } { 2 } k x ^ { 2 } elastic energy =21​kx2

A ping pong ball and a bowling ball are moving with the same momentum. Which has the greater kinetic energy?

The change in gravitational potential energy is found by multiplying an object's change in elevation by its

In the following equation, what does the k stand for? elastic energy =12kx2\text { elastic energy }=\frac{1}{2} k x^{2} elastic energy =21​kx2

How much kinetic energy does a 3kg soccer ball have while moving at 20 m/s20 \mathrm {~m} / \mathrm { s }20 m/s toward your opponents' goal?

What is the SI unit for kinetic energy?

Energy is a fundamental dimension.

Work is found by multiplying force by what other physical quantity?

Thermal energy transfer is called

What are the SI units for heat?

How much kinetic energy does a soccer ball have while moving at 20 m/s20 \mathrm {~m} / \mathrm { s }20 m/s toward a goal?

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

In the following equation, what does the x stand for? $\text { elastic energy } = \frac { 1 } { 2 } k x ^ { 2 }$

In the following equation, what does the k stand for? $\text { elastic energy }=\frac{1}{2} k x^{2}$

How much kinetic energy does a 3kg soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward your opponents' goal?

How much kinetic energy does a soccer ball have while moving at $20 \mathrm {~m} / \mathrm { s }$ toward a goal?