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Rogue Physicist.  Free resources for physics education © 2006-2016 Dorian Pascoe.  Email: dorian.pascoe@hotmail.co.uk

Most resources are available under a Creative Commons Licence.  Visit our mirror at www.physicsweb.altervista.org

 

 

 

 

Acceleration

 

 

 

 

Objectives:

 

  
 

 

 

Zoom zoom!

  

 

• To know what accelerating means.

 

 

• To know the units used to measure acceleration, and the different notations for recording them.

 

 

• Be able to explain what is meant by a rate of acceleration.

 

 

• Be able to solve numerical problems involving changes of speed.

 

 

  

 

 

 

 

 

 

Task 1 - Starter:

 

  
 

 

Now that's a fast car!

 

 

  

 

Answer the questions below.  Show full working and remember to give units with your answers.

 

 

1) A boat travels 45m in 20 seconds. What speed is the boat travelling?

 

 

2) A cyclist is travelling at 8m/s.  How long will it take him to travel 1km?

 

 

3) An aeroplane travels at 245m/s. How far will it travel in one minute? Give your answer in metres and then convert it to km.

 

  

 

 

 

 

 

 

 

 

Task 2 - Describing acceleration

 

  
 

 

Looking good!

 

 

Run!

 

 

 

 

 

  

 

Discuss with the person next to you:

 

 

1) What does accelerating mean? 

 

 

2) What does acceleration mean?

 

 

3) What units could you use to measure acceleration?

 

 

4) How could you compare the acceleration of two vehicles?

 

 

 

Hint: A Ferrari and a Fiesta can both easily reach a speed of 30 m/s (about 60mph), but is the acceleration the same?  What is different?

 

  

 

 

 

 

 

 

Answers

 

  
 

 

 

Go Turbo!

 

  

 

1) Accelerating means "increasing speed" or "getting faster".

 

 

2) Acceleration is the rate of change of speed of an object.   This means how much the object's speed changes each second.

 

 

3) We usually measure acceleration in units of metres per second per second (m/s/s).  If an object accelerates at a rate of 2m/s/s its speed increases by 2m/s each second.

 

 

4) You could measure the time taken to reach a certain speed.

 

 

*These units can also be written as m/s2 or ms-2.

 

  

 

 

 
 

 

 

Task 3 - A formula for acceleration

 

  
 

 

Calculations!  Yeah!

 

 

  

 

We can use a formula to solve numerical problems involving acceleration.  Your teacher will show you how.

 

 

acceleration = change in speed ÷ time

 

 

• Acceleration is measured in m/s/s.

• Change in speed is measured in m/s.

• Time is measured in seconds (s).

 

Note:

Metres per second can be written as either m/s or ms-1.

Metres per second per second can be written as m/s/s or m/s2 or ms-2.

  

 

 

 

 

 

Alternative formula

 

  
 

 

Calculations!

Woop woop!

 

  

 

There is an alternative formula we can use to calculate acceleration:

 

a = v - u

     t

 

 

a = acceleration (m/s/s or m/s2 or ms-2)

v = final velocity (m/s or ms-1)

u = initial velocity (m/s or ms-1)

t = time taken (s)

 

 

 

Your teacher will tell you which formula to use.

 

  

 

 

 

 

 

 

 

Task 4 - Calculations

 

  
 

 

Calculations!

AWESOME!

 

  

 

Answer the questions on this sheet.  Your teacher will show you how to do the first one.

 

Click the image above to download this question sheet.

 

 

  

 

 

 

 

 

 

 

 

 

Homework

 

  
 

 

Think hard!

Complete this homework task on Earth, or a suitable alternative planet.

  

 

Stick this homework sheet into your exercise book.

 

Click the image above to download this homework task.

 

Answer all the questions showing full working for each calculation.