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ENERGY CANNOT BE CREATED NOR DESTROYED!
ENERGY CAN CHANGE FORM, BUT THE TOTAL REMAINS CONSTANT.
Where does the energy go?
Where does the energy go?
In the room, you will find a variety of different balls (tennis, basketball, soccer ball, racquetball, etc) and a variety of different surfaces.
Choose a ball and a surface.
Drop the ball from a specific height, describe any observations that you may have.
As a group, decide on which measurements you can take regarding the bouncing ball.
Can you predict the height of the 5th bounce?
Repeat with a second ball and surface.
Class experimentation:
Class experimentation:
While you may have several quality questions to explore regarding the bouncing ball, we will be collecting similar data so that we can discuss how to process our data together.
Make your own copy HERE or use the sheet provided in Google Classroom.
Choose a ball and a surface.
Choose a starting height (top, bottom or middle of the ball) as long as it is consistent.
Release the ball and allow it to bounce 4 times. Measure the height of the rebound.
Coefficient of Restitution (e)
Coefficient of Restitution (e)
The coefficient of restitution (e) is a description of the 'bounciness' of an object (ball) when hitting a surface. The COR can be determined by determining the ratio of speeds of a falling object, from when it hits a given surface to when it leaves the surface. Or from a comparison of the heights, shown in the equation to the right. It is also an indication of the conservation of energy in a collision.
The value of the COR depends on both the ball and the type of floor. More specifically it describes the change in velocity of both the ball and the floor (as shown with the two balls below.
The variable e is used to describe the COR.
e = 0.0
If the object (ball) bounces back to the original height, the COR has a value of 1.0 (perfectly elastic). If the ball (clay) does not bounce at all the COR is 0.0 (perfectly inelastic / plastic).
0.0 < e < 1.0
Energy Measurement CER
Energy Measurement CER
On a whiteboard:
System model: Draw a system model showing the boundaries of the system and any inputs or outputs.
Identify Forms of Energy: The forms of energy present at various points in the motion of the ball.
Claim: State a claim about the differences in the bouncing of the ball(s) or surface(s).
Evidence: Using information from your graphs, provide evidence to support your claim. You can combine both graphs onto one.
Reasoning: Provide reasoning based upon your evidence to support your claim.
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