Forces | AQA GCSE Combined Science Trilogy Physics, Higher tier (8464)

Forces

306 questions
17 subtopics
Physics Paper 2
Physics Paper 2

Forces is examined in Physics Paper 2.

It covers scalars, vectors, forces and the resultant force, gravity, work done and energy transfer, stretching, compressing, and the spring constant, linear and non-linear extension, and work done on a spring, resolving forces and free body diagrams, distance, displacement and speed, the speed of sound, and the distance-speed-time equation, velocity and the distance-time relationship, acceleration, deceleration and velocity-time graphs, area under a velocity-time graph, and the uniform acceleration equation, Newton's First Law, Newton's Second and Third Laws, stopping distance and reaction time, factors affecting braking distance, braking force, deceleration and the dangers of stopping quickly and momentum and its conservation.

Sample questions from Forces

Answer each one closed book first, then open the answer.

Scalars, vectors, forces and the resultant force

What is a force?

Show the answer
A force is a push or a pull acting on an object because of its interaction with another object.
Work done and energy transfer

A shopper carries a bag horizontally at a constant height. Explain why no work is done by the upward force supporting the bag.

Show the answer
The bag moves at right angles to that force, so no distance is moved along its line of action.
Linear and non-linear extension, and work done on a spring

Write the equation for the energy stored in a stretched spring using symbols.

Show the answer
Eₑ = ½ke², where k is the spring constant and e is the extension.
Distance, displacement and speed

A cyclist ends a journey 5 km east of the start. State the cyclist's displacement in full.

Show the answer
The displacement is 5 km to the east, giving both the size and the direction.
Velocity and the distance-time relationship

Sort distance, displacement, speed and velocity into scalars and vectors.

Show the answer
Distance and speed are scalars; displacement and velocity are vectors.
Area under a velocity-time graph, and the uniform acceleration equation

A car starts from rest and accelerates uniformly at 2 m/s² over a distance of 100 m. Calculate its final velocity.

Show the answer
The final velocity is 20 m/s, because v² = 2 × 2 m/s² × 100 m = 400.
Newton's Second and Third Laws

In the equation F = m a, in what unit must the acceleration be given?

Show the answer
In metres per second squared, m/s².
Factors affecting braking distance

Explain why worn tyres lengthen the braking distance of a car.

Show the answer
Worn tyres grip the road less well, so there is less friction to slow the car and it travels further before stopping.

The 17 subtopics

One subtopic is one session. Work down the list.

Subtopic	What it covers	Questions
Scalars, vectors, forces and the resultant force	Scalar and vector quantities and why velocity is a vector, representing vectors with arrows, contact and non-contact forces with examples of each, force as a vector and the pair of forces produced when two objects interact, and finding the resultant of forces acting along a straight line.	22
Gravity	Weight and why objects near the Earth have it, how weight depends on mass and gravitational field strength, the equation W = mg in words and symbols with calculations, the units of weight, mass and gravitational field strength, centre of mass, weight in direct proportion to mass, and measuring weight with a newtonmeter.	18
Work done and energy transfer	When work is and is not done on an object, the equation for work done in words and symbols with calculations, the units of work, force and distance, the joule and the newton-metre, the energy transfer when a crane lifts a load, and how work done against friction heats a car's brakes.	17
Stretching, compressing, and the spring constant	The forces that stretch, compress and bend objects, elastic and inelastic deformation, extension proportional to force up to the limit of proportionality, the equation linking force, spring constant and extension with its units, compressing rather than stretching, and the elastic potential energy stored as work is done on a spring.	18
Linear and non-linear extension, and work done on a spring	Finding the spring constant from force and extension or from a graph, what linear and non-linear mean, the energy stored in a stretched spring, and a method for investigating extension.	26
Resolving forces and free body diagrams	The forces on a book on a table and a boat crossing a lake, free body diagrams, balanced forces at a steady speed, the resultant of forces that do not act along one line, resolving a force into two components at right angles, and scale diagrams for finding a resultant and showing forces in balance.	12
Distance, displacement and speed	Distance as a scalar and displacement as a vector with magnitude and direction, speed as a scalar that rarely stays constant, the factors affecting how fast people walk, run and cycle, typical speeds for walking, running, cycling, cars and aeroplanes, and other things whose speed varies.	18
The speed of sound, and the distance-speed-time equation	A typical speed of sound in air, measuring speed from distance and time, the equation s = v t in words and symbols with its units and calculations, rearranging it for time, and calculating average speed for journeys in which the speed keeps changing.	16
Velocity and the distance-time relationship	Velocity as speed in a given direction and how it differs from speed, sorting scalars and vectors, changing velocity at constant speed in circular motion, distance–time graphs and finding speed from their gradient, a horizontal line for a stationary object, a curve for an accelerating one, and finding speed at an instant from a curved graph.	16
Acceleration, deceleration and velocity-time graphs	The equation for average acceleration with its units and the meaning of ∆v, deceleration and negative acceleration, estimating the accelerations of a sprinter and a car, finding acceleration from the gradient of a velocity–time graph, distance travelled from the area under it, and what horizontal and downward-sloping lines show.	21
Area under a velocity-time graph, and the uniform acceleration equation	Finding distance from the area under a curved velocity-time line, the equation linking final velocity, initial velocity, acceleration and distance, free fall at 9.8 m/s², and terminal velocity.	16
Newton's First Law	What Newton's First Law says about zero resultant force, what happens to stationary and moving objects when forces balance, why a car reaches a top speed, and what inertia means.	14
Newton's Second and Third Laws	How resultant force, mass and acceleration are linked, the units in F = m a, inertial mass, investigating force and acceleration with a trolley, and the equal and opposite forces of Newton's Third Law.	25
Stopping distance and reaction time	Stopping, thinking and braking distance, how an increase in speed affects stopping distance, how reaction times vary and the things that lengthen them, measuring reaction time with a ruler-drop test and repeating it, and why a tired driver has a longer thinking distance.	22
Factors affecting braking distance	The factors that lengthen braking distance, including icy and wet roads and worn brakes and tyres, whether heavy rain affects thinking or braking distance, leaving a bigger gap in icy weather, checking tyre tread, lower speed limits outside schools, and estimating braking distance when speed doubles or the road is wet.	16
Braking force, deceleration and the dangers of stopping quickly	The energy transfer when brakes are applied, how speed affects the braking force needed, how braking force sets deceleration, and the dangers of overheating brakes, skidding and large forces on passengers.	14
Momentum and its conservation	Momentum as mass times velocity in words and symbols with its units and calculations, the momentum of a stationary object, conservation of momentum in a closed system, and explaining skaters pushing apart, colliding trolleys that join together and a recoiling rifle.	15

Forces is 306 of the 1,093 questions in the guide.Get the guide, £7

How the guide is worked

Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.

Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.

Read the full method, the return schedule and the research behind it.