Under what condition can the suvat equations be used?

Constant acceleration in a straight line.

What does the gradient of a displacement–time graph give?

The velocity (the gradient of the tangent gives instantaneous velocity).

What does the area under a velocity–time graph give?

The displacement (areas below the time axis are negative).

How do you find the instantaneous acceleration from a curved velocity–time graph?

Draw a tangent at that time and calculate its gradient.

In the free-fall core practical, which graph gives g, and how?

Plot h against t²; the gradient is g/2, so g = 2 × gradient.

Name one source of error in a free-fall timing experiment and a fix.

Residual magnetism delaying release: use a non-magnetic release or a thin sheet of paper; or repeat and average.

A ball is thrown upwards. What is its velocity at the highest point and its acceleration there?

Velocity is zero; acceleration is still g (9.81 m s⁻²) downwards.

Uniformly accelerated motion and motion graphsEdexcel A-Level Physics: Flashcards

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Question

State the equation for velocity in terms of u, a and t when acceleration is constant.

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State the equation for velocity in terms of u, a and t when acceleration is constant.: v = u + at
Which suvat equation contains no time?: v² = u² + 2as
Which suvat equation contains no final velocity?: s = ut + ½at²
Under what condition can the suvat equations be used?: Constant acceleration in a straight line.
What does the gradient of a displacement–time graph give?: The velocity (the gradient of the tangent gives instantaneous velocity).
What does the gradient of a velocity–time graph give?: The acceleration.
What does the area under a velocity–time graph give?: The displacement (areas below the time axis are negative).
What does the area under an acceleration–time graph give?: The change in velocity.
How do you find the instantaneous acceleration from a curved velocity–time graph?: Draw a tangent at that time and calculate its gradient.
What is the shape of the displacement–time graph for uniform acceleration from rest?: A parabola (s = ½at²).
In the free-fall core practical, which graph gives g, and how?: Plot h against t²; the gradient is g/2, so g = 2 × gradient.
Name one source of error in a free-fall timing experiment and a fix.: Residual magnetism delaying release: use a non-magnetic release or a thin sheet of paper; or repeat and average.
A ball is thrown upwards. What is its velocity at the highest point and its acceleration there?: Velocity is zero; acceleration is still g (9.81 m s⁻²) downwards.

Exam questions on Uniformly accelerated motion and motion graphs

A train leaves a station and accelerates uniformly from rest. After 40 s it has reached a speed of 20 m s⁻¹. It then continues at this constant speed.
The train then travels at 20 m s⁻¹ for a further 90 s. Calculate the total distance travelled in the 130 s.2 marks
A student investigates free fall by dropping a small steel ball from rest. A timer starts when the ball is released and stops when the ball strikes a trapdoor switch 1.50 m below. Air resistance may be ignored.
In one trial the ball takes 0.560 s to fall the 1.50 m. Calculate the value of g given by this trial.2 marks
A lift in a tall building starts from rest at the ground floor. It accelerates uniformly at 1.2 m s⁻² for 3.0 s, moves at constant velocity for 8.0 s, then decelerates uniformly to rest in 2.0 s.
Calculate the maximum speed reached by the lift and the magnitude of its deceleration in the final stage.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).