Energy & Work

Lesson: Energy and Work

By William Lovering

Multiple Choice

What kind of energy is in a moving skateboard?

• Potential
• Kinetic

Multiple Choice

What kind of energy is in a rock at the edge of a cliff?

• Potential
• Kinetic

Multiple Choice

What kind of energy is in a battery?

• Potential
• Kinetic

Calculating Energy

Energy is measured in units called Joules.

Kinetic energy requires something to be moving. That means objects with kinetic energy have a velocity.

The formula to calculate kinetic energy is

E_k = (0.5)(m​)(v²)

KE = 1/2mv²

Multiple Choice

A cheetah can run briefly with a speed of 31.0 m/s. Suppose a cheetah with a mass of 47.0 kg runs at this speed. What is the cheetah’s kinetic energy?

• 1457 Joules

• 22,584 Joules

• 15 Joules

• 45,167Joules

Calculating Energy

Potential Energy does not have motion so it must be calculated differently.

A common form of potential energy is gravitational potential energy (GPE). GPE is energy stored due to an object's position and the force of gravity. To calculate GPE you use this formula:

E_p = mgh (Potential Energy = mass x acceleration from gravity x height)​

Subject | Subject

GPE = mgh

Multiple Choice

Which object has the most graviational potential energy?

• A 1000kg car lifted 0.02m off the ground.

• A 0.5kg baseball 20m off the ground

• A 75kg weight lifted 1m off the ground

• A 12kg crate 3m off the ground.

Multiple Choice

When a pendulum swings, at which point is kinetic energy highest?

• 1
• 2
• 3
• 4

Multiple Choice

A ball is projected into the air. Where is potential energy the greatest?

Multiple Choice

What is the GPE at point A

• 14 J

• 12 J

• 6 J

• 8 J

Multiple Choice

What is the KE at point B?

• 14 J

• 12 J

• 6 J

• 8 J

Multiple Choice

What is the Total Energy of the system?

• 14 J

• 12 J

• 6 J

• 8 J

Multiple Select

What are the two main forms of energy?

• kinetic energy

• potential energy

• light

• sound

Multiple Choice

The rock in the picture is pushed over the edge and it begins to fall. Which type of energy conversion is taking place?

• mechanical to heat

• sound to mechanical

• potential to kinetic

• kinetic to potential

Multiple Choice

It takes 20 N of force to move a box a distance of 10 m. How much work is done on the box ?

• 200 J
• 20.0J
• 2 J
• 200 N

Multiple Choice

Two factors that determine work are

• amount of the force, and effort used
• amount of the force, and type of force
• mass, and distance
• amount of force and distance moved

Multiple Choice

The unit or label for work is

• netwons
• joules
• meters
• seconds

Multiple Choice

if you push a cart with a force of 60 N resulting in 120 J of work.. how far did you move the cart? 

• 7200 m
• 0 m
• 2 N 
• 2 m

Multiple Choice

Two people shove on a wall with 100 N. The wall doesn’t move. How much work is done?

• 100J

• 100N

• 0J

• 0N

Multiple Choice

A student turns on flashlight. What is the energy conservation that happen there?

• chemical - light - electrical

• electrical - chemical - light

• chemical - electrical - light

• light - chemical - electrical

Multiple Choice

A person boils water by using electrical stove. What type of energy conservation there?

• heat - electrical

• electrical - heat

• sound - heat

• heat - light

Multiple Choice

What is the formula of work?

• W = F / d

• W = F + d

• W = F x d

• W = F - d

Multiple Choice

An object weighing 20 N moves horizontally toward the right a distance of 5.0 m. What is the work done on the object by the force of gravity?

• The work done on the object by the force of gravity is 50 J.

• The work done on the object by the force of gravity is zero joules.

• The work done on the object by the force of gravity is 4.0 J.

• The work done on the object by the force of gravity is 0.25 J.

• The work done on the object by the force of gravity is 100 J.

Multiple Choice

If the net work done on an object is positive, what can you conclude about the object's motion?

• The object is speeding up.

• The object is moving with a constant velocity.

• The object is slowing down.

• The object is at rest; its position is constant.

Multiple Choice

In which of the following situations do your arms do work on books?

• holding a heavy stack of books while standing

• dropping a stack of books onto a table

• picking up a pile of books from the floor

• carrying a heavy stack of books

Multiple Choice

Using the scientific definition, which statement is always true of work?

• It is difficult.

• It is done with a machine.

• It involves levers.

• It involves a transfer of energy.

Multiple Choice

When a body falls freely towards the earth, then its total energy

• (a) increases

• (b) decreases

• (c) remains constant

• (d) first increases and then decreases

Multiple Choice

A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car

• (a) does not change

• (b) becomes twice to that of initial

• (c) becomes 4 times that of initial

• (d) becomes 16 times that of initial