2.13 & 2.14 Energy Conservation & Energy Conservation Math

• Kinetic and Potential Energy
• 6th Grade

Today's Objective

We will explain mechanical energy conservation and use the formulas to determine conservation of energy.

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Where is the kinetic energy of the pendulum the greatest?

1. At the top
2. At the bottom
3. Halfway in between the top and bottom
4. It remains constant

When is the skateboarder's kinetic energy the greatest?

1. At the top of the half-pipe.
2. At the bottom of the half-pipe.
3. Halfway in between the top and bottom of the half-pipe.
4. The kinetic energy remains constant.

Where is the kinetic energy of the pendulum the greatest?

1. At the top
2. At the bottom
3. Halfway in between the top and bottom
4. It remains constant

When is the skateboarder's potential energy the greatest?

1. 15 J
2. 5 J
3. 22.5 J
4. 7.5 J

An object has a mass of 2.0 kg and a speed of 5 m/s. What is the kinetic energy of the object?

1. 10 J
2. 5 J
3. 25 J
4. 98 J

An object is at a height of 7 m. It has a mass of 4.0 kg. Calculate the gravitational potential energy.

1. 28 J
2. 56 J
3. 274 J
4. 500 J

What causes the
loss of energy?

Discussion Question

Imagine a boy on a slide. As the boy slides down, his PE is turning into KE. But he is also feeling the effects of friction slowing him down. Friction is a force, and it is acting for a distance. Is mechanical energy 

conserved?

Discussion Question

When skydiving, what causes the energy to decrease allowing the skydiver to decrease his/her velocity prior to hitting the ground?

When is mechanical energy conserved?

When is mechanical energy actually conserved?

Using Energy Equations

You can use the energy equations to answer these types of questions.

How to solve for final kinetic energy.

1. Plug in the information into the formula.
2. Solve with what you have. (multiply the left side, then multiply the right)
3. Divide through to get v2 by itself. 
4. Find the square root to determine the final ke.

An object has a kinetic energy of 25 J and a mass of 34 kg , how fast is the object moving?

Steps to Solve :

1. Plug in the information into the formula.

2. Solve with what you have. (multiply the left side, then multiply the right)

3. Divide through to get v2 by itself. 

4. Find the square root to determine the final ke.

A bowling ball with a mass of 2 kg falls from the top of a building 10 meters off the ground. How fast will it be traveling just before it hits the ground?

An object has a kinetic energy of 25 J and a mass of 34 kg , how fast is the object moving?

Linear and Positive

Linear and Negative

Non Linear Postive

Non Linear Negative

Describe the relationship between kinetic energy and speed according to the chart.

1. linear and positive
2. linear and negative
3. non linear and positive
4. non linear and negative

Describe the relationship between kinetic energy and speed according to the chart.

1. linear and positive
2. linear and negative
3. non linear and positive
4. non linear and negative

Describe the relationship between kinetic energy and speed according to the chart.

1. linear and positive
2. linear and negative
3. non linear and positive
4. non linear and negative

Describe the relationship between kinetic energy and speed according to the chart.

1. linear and positive
2. linear and negative
3. non linear and positive
4. non linear and negative

Exit Ticket Quiz

Take the 2.10 KE and PE math Practice