Forces and their Effects - Key Concepts for GCSE Physics

Physics Quiz - Forces - Forces and their Effects (Questions)

Find out how forces change motion and shape, from pushing and pulling to stretching and squashing, and see how different materials respond when forces are applied.

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Fascinating Fact:

Forces can stretch, compress, or bend objects, and some materials return to their original shape when the force is removed.

In GCSE Physics, you study how forces change the motion and shape of objects. You will learn to draw force diagrams, calculate resultant forces and describe stretching, squashing and bending in everyday situations.

Key Terms

Force: A push or pull that can change the speed, direction or shape of an object, measured in newtons (N).
Resultant force: The single force that has the same effect as all the individual forces acting on an object combined.
Deformation: A change in shape caused by a force, which can be elastic if the object returns to its original shape or plastic if it does not.

Frequently Asked Questions (Click to see answers)

What is a force in GCSE Physics?

In GCSE Physics, a force is a push or pull that can change an object’s motion or shape. Forces are vectors, measured in newtons, and they have both size and direction.

What is the difference between balanced and unbalanced forces?

Balanced forces have a resultant force of zero, so there is no change in motion. Unbalanced forces give a non zero resultant force, causing acceleration, deceleration or a change in direction.

How do forces cause stretching and compression of objects?

When a force pulls on an object it can stretch it, and when a force pushes it can compress it. If the material is elastic it will return to its original length when the force is removed.

Try These Related Quizzes

What can affect the speed of a car?

[ ]	Air resistance
[ ]	Power of the engine
[ ]	Mass of the car
[ ]	All of the above

As the speed of a car increases, what happens to the strength of the air resistance?

[ ]	Decreases
[ ]	Increases
[ ]	Stays the same
[ ]	There is no air resistance

How can the acceleration of an object be measured on a velocity time graph?

[ ]	By calculating the area under the graph
[ ]	By measuring the gradient
[ ]	By calculating the area above the graph
[ ]	You cannot work out the acceleration of an object from a velocity time graph

If the resultant force acting on an object is zero, what happens to the object?

[ ]	It does not move
[ ]	It continues to move at a constant speed
[ ]	It does not accelerate
[ ]	All of the above

When a resultant force acts upon an object, what determines the size of the acceleration of that object?

[ ]	Size of resultant force
[ ]	Mass of the object
[ ]	Size of resultant force and mass of the object
[ ]	Neither size of resultant force nor mass of the object

In a vacuum, all bodies accelerate at what?

[ ]	The same rate
[ ]	A rate determined by their mass
[ ]	No two bodies accelerate at the same rate
[ ]	Either two times the strength of the field present or four times the strength of the field present

Which of the following surfaces will have the greatest frictional force?

[ ]	Smooth surface
[ ]	Rough surface
[ ]	Both smooth and rough have the same frictional force
[ ]	It is impossible to tell

The equation that links mass, force and acceleration is ...

[ ]	Force = acceleration / mass
[ ]	Mass = force x acceleration
[ ]	Force = mass x acceleration
[ ]	Acceleration = mass x force

When is the terminal velocity of an object reached?

[ ]	When the acceleration is 0
[ ]	When the acceleration is 1
[ ]	When the acceleration is less than 0
[ ]	When the acceleration is more than 1

10.

How can distance travelled be calculated by using a velocity time graph?

[ ]	It is the area under the graph
[ ]	It can be calculated from the gradient of the graph
[ ]	It cannot be calculated using a velocity time graph
[ ]	It is the area above the graph

Physics Quiz - Forces - Forces and their Effects (Answers)

What can affect the speed of a car?

[ ]	Air resistance
[ ]	Power of the engine
[ ]	Mass of the car
[x]	All of the above

It is all about resultant forces and inertia

As the speed of a car increases, what happens to the strength of the air resistance?

[ ]	Decreases
[x]	Increases
[ ]	Stays the same
[ ]	There is no air resistance

Air resistance is caused by the car hitting the molecules of the gases that make up the atmosphere

How can the acceleration of an object be measured on a velocity time graph?

[ ]	By calculating the area under the graph
[x]	By measuring the gradient
[ ]	By calculating the area above the graph
[ ]	You cannot work out the acceleration of an object from a velocity time graph

The gradient is measuring how the velocity of the object has changed over a time period which is what acceleration is all about

If the resultant force acting on an object is zero, what happens to the object?

[ ]	It does not move
[ ]	It continues to move at a constant speed
[ ]	It does not accelerate
[x]	All of the above

It depends on the state of the object when the resultant force is zero. This often sounds odd as instinct tells us that zero force would mean no movement. That's true but this is about resultant forces which can change at any time. So if it changes to zero when the object is moving, it will continue to move exactly as it was when the resultant force hit the zero mark

When a resultant force acts upon an object, what determines the size of the acceleration of that object?

[ ]	Size of resultant force
[ ]	Mass of the object
[x]	Size of resultant force and mass of the object
[ ]	Neither size of resultant force nor mass of the object

Larger masses will be accelerated more slowly for the same resultant force. Using a larger resultant force on a given mass will cause it to accelerate faster (and vice-versa of course for both cases!)

In a vacuum, all bodies accelerate at what?

[x]	The same rate
[ ]	A rate determined by their mass
[ ]	No two bodies accelerate at the same rate
[ ]	Either two times the strength of the field present or four times the strength of the field present

What stops a feather falling at the same rate as a stone on Earth is the amount of air resistance each object feels. In a vacuum, this restrictive force is removed and both objects will fall at the same rate. This was famously demonstrated by the Apollo 15 astronaut, David Scott, at the very end of their final Moon walk

Which of the following surfaces will have the greatest frictional force?

[ ]	Smooth surface
[x]	Rough surface
[ ]	Both smooth and rough have the same frictional force
[ ]	It is impossible to tell

Drivers need to take more care when braking on smooth road surfaces especially when they are wet as friction is lower

The equation that links mass, force and acceleration is ...

[ ]	Force = acceleration / mass
[ ]	Mass = force x acceleration
[x]	Force = mass x acceleration
[ ]	Acceleration = mass x force

This is Newton's second law. You will need to be able to rearrange it to work out the mass or acceleration when given the other two figures