Unit 3: Work, Energy, and Power

Question 1

What is the formula for work done (W)?

Answer 1

W = F × d × cos(θ)

Question 2

True or False: Work is a scalar quantity.

Answer 2

True

Question 3

What unit is work measured in?

Answer 3

Joules (J)

Question 4

Fill in the blank: The work-energy principle states that the work done on an object is equal to its change in _____.

Answer 4

kinetic energy

Question 5

What is the formula for kinetic energy (KE)?

Answer 5

KE = 1/2 mv²

Question 6

What is the unit of kinetic energy?

Answer 6

Joules (J)

Question 7

Define potential energy (PE).

Answer 7

Potential energy is the energy stored in an object due to its position or configuration.

Question 8

What is the formula for gravitational potential energy?

Answer 8

PE = mgh

Question 9

In the equation PE = mgh, what does each variable represent?

Answer 9

m = mass, g = acceleration due to gravity, h = height

Question 10

True or False: Energy can be created or destroyed.

Answer 10

False

Question 11

What is the law of conservation of energy?

Answer 11

Energy cannot be created or destroyed, only transformed from one form to another.

Question 12

What is the formula for power (P)?

Answer 12

P = W/t

Question 13

What is the unit of power?

Answer 13

Watts (W)

Question 14

Fill in the blank: Power is the rate at which _____ is done.

Answer 14

work

Question 15

What is the relationship between work, energy, and power?

Answer 15

Work is the process of energy transfer, while power is the rate of doing work.

Question 16

What is the formula for elastic potential energy?

Answer 16

PE = 1/2 kx²

Question 17

In the equation PE = 1/2 kx², what do k and x represent?

Answer 17

k = spring constant, x = displacement from the equilibrium position

Question 18

True or False: The work done by a conservative force depends on the path taken.

Answer 18

False

Question 19

What is a conservative force?

Answer 19

A force that does work independent of the path taken, such as gravity.

Question 20

What is the formula for net work done?

Answer 20

W_net = ΔKE

Question 21

What is the equation for gravitational force?

Answer 21

F_gravity = mg

Question 22

Fill in the blank: The total mechanical energy is the sum of _____ and _____ energy.

Answer 22

kinetic, potential

Question 23

What is the principle of conservation of mechanical energy?

Answer 23

In the absence of non-conservative forces, the total mechanical energy remains constant.

Question 24

What is the work done by friction?

Answer 24

W_friction = -f_friction × d

Question 25

True or False: The work done by a non-conservative force is path-dependent.

Answer 25

True

Question 26

What is the formula for the work done when a force is applied at an angle?

Answer 26

W = Fd cos(θ)

Question 27

What is the equation for average power?

Answer 27

P_avg = ΔW/Δt

Question 28

Fill in the blank: The unit of energy is the same as the unit of _____ in the International System.

Answer 28

work

Question 29

What is the relationship between kinetic energy and speed?

Answer 29

Kinetic energy is proportional to the square of the speed (v²).

Question 30

What does the spring constant (k) measure?

Answer 30

The stiffness of a spring.

Question 31

True or False: An object in free fall has only gravitational potential energy.

Answer 31

False

Question 32

What happens to the potential energy of an object as it falls?

Answer 32

It decreases as kinetic energy increases.

Question 33

What is the formula for net work when multiple forces act on an object?

Answer 33

W_net = W₁ + W₂ + ... + W_n

Question 34

Fill in the blank: The work done by a force is positive when the force and displacement are in the _____ direction.

Answer 34

same

Question 35

What is the work-energy theorem?

Answer 35

The work done by the net force on an object equals the change in its kinetic energy.

Question 36

What is the potential energy of an object at ground level?

Answer 36

Zero (PE = 0 when h = 0)

Question 37

Fill in the blank: The area under a force vs. displacement graph represents _____ done.

Answer 37

work

Question 38

What is the effect of doubling the speed of an object on its kinetic energy?

Answer 38

The kinetic energy increases by a factor of four.

Question 39

What is the formula for power in terms of force and velocity?

Answer 39

P = Fv

Question 40

What does the symbol 'θ' represent in the work formula?

Answer 40

The angle between the force and the direction of displacement.

Question 41

True or False: A heavier object has more gravitational potential energy at the same height than a lighter object.

Answer 41

True

Question 42

What is the relationship between work and energy in a closed system?

Answer 42

Work can change the energy of the system but the total energy remains constant.

Question 43

Fill in the blank: In a conservative system, the total mechanical energy is _____ during motion.

Answer 43

constant

Question 44

What is the formula for the work done against gravity?

Answer 44

W = mgh

Question 45

What is the unit of spring constant (k)?

Answer 45

N/m (Newtons per meter)

Question 46

What is the formula for the change in potential energy?

Answer 46

ΔPE = PE_final - PE_initial

Question 47

True or False: Energy can be transformed from kinetic to potential energy and vice versa.

Answer 47

True

Question 48

What is the implication of a negative work done by a force?

Answer 48

It means that the force is acting opposite to the direction of the displacement.