Bouncing Balls 1

...bouncing balls - part 1...

Objectives:

Bouncy!

• Know that the height of rebound for a bouncy ball depends on a range of factors.

• Be able to describe the energy changes taking place in a bouncy ball which has been dropped from a height.

• Be able to plan an investigation to find the relationship between height of release and height of rebound.

Task 1 - Starter

Penguins.

Oh yes.

Find someone who can:

▪ describe the energy transfer in a hairdryer.

▪ describe the energy transfer in a battery powered torch.

▪ describe the energy transfer in a bouncy ball.

▪ show all of these as energy transfer diagrams.

Your teacher will ask you to share your ideas with the class, and may write some of your ideas on the board.

Bouncy bouncy...

This video below may help to remind you about the bouncy ball!

I know what happens!

You might also be interested to see what happens when a golf ball bounces on a solid surface.

Task 2 - Variables

So much thinking...

My brain hurts.

You are going to investigate how the height of rebound of a ping-pong ball is affected by the height of release.

Your teacher will explain to you what is meant by:

▪ The independent variable, and values.

▪ The dependent variable.

▪ The controlled variables, and values.

Working in pairs, discuss the variables and values you will use for your investigation.

Write your variables and values in your exercise book.

Task 3 - Method

Writing! Yeah!

Write a method for your investigation.

Write your method as a list of detailed instructions, including specified values and details of what to measure.

Rules for a good method

▪ Instructions should be in a numbered format.

▪ Each sentence should start with a verb (e.g. place, add, or measure).

▪ Give precise quantities or measurements (e.g. 50cm³ of water).

▪ Use scientific names for apparatus.

▪ Use impersonal language (e.g. not "I will" or "you should").

Task 4 - Prediction

Think hard!

I can predict the future, using science.

Write a prediction, stating how you think the independent variable and dependent variable be connected.

Use scientific ideas and reasoning to support your assertions.

Guidance for a good hypothesis

Part 1 - Explaining the science:

▪ State the type of energy the ball has before being released.

▪ Explain why the amount of energy depends on the release height.

▪ Describe the energy changes which take place when the ball bounces.

▪ Explain why it bounces to a lower height than the height it was dropped from.

Part 2 - prediction, linked to your scientific reasoning:

▪ State how you think the independent and dependent variables will be connected.

"As I increase/decrease the ____________, I think that ______________ will increase or decrease".

▪ Link your prediction to the science, by giving reasons to justify your prediction.

Task 5 - Bouncy or not?

Think hard!

Your teacher will show you some happy and sad balls.

They look identical...

Think hard!

...but they behave very differently when dropped! Can you explain why?

Think about what is happening to the energy in each case!

Homework

Bounce!

Design a results table to collect the results of your experiment.

Remember to include:

• A column for the drop height.

• 3 columns for your repeat readings of the bounce height.

• A column for the average bounce height.

• A header row with units and descriptive headings.

There is a copy of the table you can print for students here or a skeleton results table here, if you do not want to set this task as a homework.