Oxford Activities

From Kerboodle

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Theme A. Space, time & motion

A.1 Falling with style

Mathematics

In this activity you will consider the graphs of motion which result from situations where air resistance is assumed to be zero, and those where it is not.

Introduction

In physics we often model motion with many simplifications, for example we may model an object as a sphere or even a point when it is not and we may use terms like “air resistance is negligible” when in reality it would not be.

In this activity you will describe situations where air resistance is assumed to be zero and those where it is not, and consider the graphs of motion which would result from both cases.

Now complete the questions on the following screens.

Question 1

Select the correct words to complete the information about freefall through the atmosphere.

Initially a skydiver will accelerate towards the ground at 9.8 m s⁻² because the downwards force of their is acting on them unopposed.

As they start to move through the atmosphere will act upwards and this will reduce the acceleration.

The air resistance will as the downwards speed increases.

Eventually the air resistance and weight will and the resultant downwards force will be zero.

This will mean that the speed of the diver is constant, this velocity is known as the speed.

Question 2

The world record for a high-altitude jump is a fall from a height of 39 km.

Assuming that the downwards acceleration was a constant 9.8 m s⁻² and air resistance was negligible, calculate the time it would take the skydiver to reach the ground.

• 796 s

• 874 s

• 63 s

• 89 s

Question 3

In reality, the skydiver took a time of 480 s to fall from the height of 39 km.

Calculate the mean acceleration the skydiver experienced during the fall.​​​​​​​

• 8.3 m s⁻²

• 0.34 m s⁻²

• 0.23 m s⁻²

• 2.3 m s⁻²

Question 4

The graph shows how different factors change when a skydiver is falling, assuming no air resistance.

Select the correct options to complete the statements about the graph.

If there is no air resistance, then:

• the acceleration could be represented by line

• the velocity could be represented by line

• the distance fallen could be represented by line

Question 5

The graph shows how different factors change when a skydiver is falling, assuming there is air resistance.

Select the correct options to complete the statements about the graph.

If there is air resistance, then:

• the magnitude of the air resistance could be represented by line

• the acceleration could be represented by line

• the velocity could be represented by line

• the distance fallen could be represented by line

Question 6

How can the acceleration of a skydiver be determined from a speed–time graph?

• The intercept on the y-axis.

• The intercept on the x-axis.

• The gradient of the line.

• The area beneath the line on the graph.

Question 7

How can the distance travelled by a skydiver be determined from a speed–time graph?

• The intercept on the x-axis.

• The gradient of the line.

• The intercept on the y-axis.

• The area beneath the line on the graph.

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Answers

1. weight, air resistance, increase, become equal, terminal

2. 89 s

3. 0.34 m s⁻²

4. A, B, D

5. C, A, C, D

6. The gradient of the line

7. The area beneath the graph

A.1 Kinematics: My self study quiz

A.1 Kinematics: Vocabulary activity

A.1 Motion: Skills activity

A.1 Scalars and vectors: Skills activity

Theme B. The particulate nature of matter