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

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

 

 

 

 

Terminal Speed

 

 

 

 

Objectives:

 

  
 

 

 

Go, little monkey!

  

 

• Know that air resistance acts on moving objects and increases with speed.

 

 

• Be able to explain why falling or moving objects reach terminal speed.

 

 

• Be able to sketch and explain a speed-time graph for a falling object.

 

  

 

 

 

 

 

 

Task 1 - Starter:

 

  
 

 

 

 

 

  

 

Find someone who knows:

 

 

1) The difference between mass and weight.

 

2) The units used to measure mass.

 

3) The units used to measure weight.

 

4) What is the weight of 1kg on Earth.

 

  

 

 

 

 

 

 

Task 2 - Terminal velocity

 

  
 

 

 

Forces on a skydiver.

  

 

Watch this video which explains how the motion of a skydiver changes according to the sizes of the forces acting.

 

 

Video credit: BBC bitesize.

Click the image above, or follow this link.

 

  

 

 

 

 

 

 

 

Task 3 - Graphing motion for a skydiver

 

  
 

 

Monkey skydiver!

  

 

Your teacher will give you a copy of this data, which shows the velocity of a skydiver against time.

 

 

 

 

Plot a velocity-time graph of the data and label these points/sections on your graph:

 

 

A) Where the skydiver leaves the aircraft.

 

B) Where the skydiver is accelerating at about 10m/s2.

 

C) Where air resistance is building up.

 

D) Where air resistance and gravity balance.

 

E) Where the parachute opens.

 

F) Where the skydiver is falling at a steady speed with the parachute open.

 

 

 

Teacher note - there is a copy of the finished graph here.

 

  

 

 

 

 

 

 
 

 

 

Task 4 - Exam questions

 

  
 

 

AHHH!  I'M FALLING!

 

 

  

 

Ideas about terminal speed are regularly used as topics for examination questions.

 

 

 

Complete question 2 from this examination paper (foundation) and question 2 from this examination paper (higher) to check your understanding.

 

 

 

Extension:

Try Q4 from this examination paper.  Use the formula sheet in the front of your exercise book to help you.

 

  

 

 

 

 

 

 

 

Homework

 

  
 

 

 

  

 

Explain in detail the size and direction of the forces a skydiver experiences as he falls from an aeroplane, and how these forces affect his motion.

 

You should include:

 

1) How he/she reaches terminal velocity during free-fall.

 

2) How he/she reaches terminal velocity with the parachute open.

 

You only need to consider the vertical forces acting - not horizontal motion or forces.  Your explanation should cover at least half a side of A4.  This planning skeleton may help you to structure your explanation.

 

Click the image above to download this planning skeleton.