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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

 

 

 

 

Resultant Forces 1

 

 

 

 

Objectives:

 

  
 

 

 

Forces.

  

 

• Know that multiple forces acting on an object can be combined into a single resultant force.

 

 

• Be able to work out the size and direction of the resultant force acting on an object.

 

 

• Be able to describe how the resultant force acting on an object will change the motion of the object.

 

 

• Be able to recognise whether forces are balanced or unbalanced.

 

  

 

 

 

 

 

 

 

Task 1 - Starter: forces on a cyclist

 

  
 

 

 

I know about forces!

 

  

 

Forces can cause objects to start moving, stop moving, speed up and slow down.  This video explains how forces affect a cyclist.

 

Video credit: BBC bitesize.

 

  

 

 

 

 

 

 

Task 2 - Resultant forces

 

  
 

 

Forces.  Grrr!

 

  

 

Your teacher will explain what is meant by balanced forces, unbalanced forces, and resultant forces.

 

 

Decide whether the forces are balanced or unbalanced for each of the scenarios below, and work out the size and direction of the resultant force in each case.

 

Click the image above to download it as a powerpoint slide.

 

  

 

 

 

 

 

 

Task 3 - Resultant forces cut and stick

 

  
 

 

 

 

You will use scissors for this task.  Be careful.

  

 

There is often more than one force acting on an object.  If the forces are unbalanced, we will need to find the resultant force.  Your teacher will explain what is meant by the term "resultant force".

 

 

Complete this task by selecting the correct arrows to produce each resultant force.

 

Click the image above to download this task as a word document.

 

  

 

 

 

 

 

 

 

Task 4 - Forces affecting motion

 

  
 

 

A hover puck.

 

 

  

 

If the forces on an object are balanced there is no resultant force.  The object will either remain stationary, or continue moving at a constant speed. 

 

Basically, it will continue doing whatever it is currently doing!

 

 

If the forces on an object are unbalanced, there is a resultant force.  This could make the object start moving, stop moving, accelerate (speed up) or decelerate (slow down).

 

 

Your teacher will demonstrate some of these scenarios using a hover puck.

 

Note that these images do not depict best kicking strategies.

 

  

 

 

 

 

 

 

 

Task 5 - Forces affecting the motion of a car

 

  
 

 

 

Science! Yeah!

 

  

 

Work out the size and direction of the resultant force and how it will affect the motion of the car, for each scenario.

 

 

Hint: think about what the car is doing before the force starts acting!

Click the image above to download this task as a word document.

 

  

 

 

 

 

 
 

 

 

Task 6 - Forces d.a.r.t.

 

  
 

 

A hover puck.

 

 

  

 

Complete the worksheet below, by deleting the incorrect parts of the text below, and filling in the missing words.

 

 

 

Click the image above to download this task as a word document.