CCEA A Level Physics
CCEA A Level Physics 1.4 Linear Motion and 1.5 Dynamics Exam Questions
Free CCEA A Level Physics revision for 1.4 Linear Motion and 1.5 Dynamics: what you need to know, common mistakes and exam-style questions with answers. Covers displacement, velocity, acceleration, equations of motion, motion graphs, measuring g with light gates and projectile motion.
Practise 1.4 Linear Motion and 1.5 Dynamics with past papers
Once you have learnt this topic, find the 1.4 Linear Motion and 1.5 Dynamics questions in real CCEA A Level Physics past papers and mark them with the mark scheme. Doing lots of real questions is the quickest way to learn how examiners ask about each idea.
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About CCEA A Level Physics 1.4 Linear Motion and 1.5 Dynamics
Linear motion and dynamics form the kinematics section of Unit AS 1: Forces, Energy and Electricity. You need to define displacement, velocity and acceleration, use the equations of uniformly accelerated motion, interpret displacement-time and velocity-time graphs, and describe how g can be measured using light gates. Section 1.5 extends this to projectiles, treating horizontal and vertical motion independently with air resistance ignored. Examiners regularly ask for a multi-step projectile calculation, the meaning of the gradient or area of a graph, and a clear description of the light gate experiment including how g is found from the data.
What you need to know
- Definitions Displacement is distance in a stated direction. Velocity is rate of change of displacement. Acceleration is rate of change of velocity, unit m s-2.
- Equations of motion For constant acceleration: v = u + at, s = ut + 1/2 at^2, v^2 = u^2 + 2as and s = 1/2(u + v)t. List s, u, v, a, t before choosing an equation.
- Motion graphs Gradient of a displacement-time graph is velocity. Gradient of a velocity-time graph is acceleration and the area under it is displacement. A curved s-t graph means changing velocity.
- Measuring g with light gates Drop an object of known length through a light gate, or through two gates, and the timer gives the time to break the beam. Calculate speeds, then use v^2 = u^2 + 2gs or a graph to find g; repeat and average.
- Projectile motion Horizontal velocity stays constant (no air resistance). Vertical motion has acceleration g downwards. Time links the two components.
- Projectile launched at an angle Resolve the launch velocity: horizontal u cos θ and vertical u sin θ. At the top of the flight the vertical velocity is zero but the horizontal velocity is unchanged.
Common mistakes in 1.4 Linear Motion and 1.5 Dynamics
- Using the equations of motion when acceleration is not constant; they only apply for uniform acceleration.
- Taking g as positive upwards and downwards in the same calculation; choose a sign convention and keep it.
- Saying a projectile has zero velocity at the top of its path; only the vertical component is zero.
- Using the gradient of a velocity-time graph to find distance; distance travelled is the area under the graph.
- Letting horizontal velocity change during flight; with no air resistance there is no horizontal force, so it stays constant.
Try three 1.4 Linear Motion and 1.5 Dynamics exam-style questions
1. A car travelling at 25 m s-1 brakes uniformly to rest in 50 m. Calculate its deceleration. (2 marks)
Show the mark scheme answer
v^2 = u^2 + 2as so 0 = 625 + 2a(50); a = -6.25 m s-2, so deceleration = 6.3 m s-2.
2. A ball is thrown horizontally at 15 m s-1 from the top of a cliff 20 m high. Calculate the horizontal distance it travels before landing. Ignore air resistance. (3 marks)
Show the mark scheme answer
Vertical: 20 = 1/2 x 9.81 x t^2; t = 2.02 s; horizontal distance = 15 x 2.02 = 30 m.
3. Describe how light gates can be used to measure the acceleration due to gravity. (4 marks)
Show the mark scheme answer
Drop an object such as a card or ball through two light gates a measured distance apart; timer records the time each gate is blocked; speed at each gate = length of object / time; g = (v^2 - u^2)/2s; repeat and average or vary separation and plot a graph.
1.4 Linear Motion and 1.5 Dynamics FAQs
What does CCEA A Level Physics 1.4 and 1.5 cover?
Displacement, velocity and acceleration, the equations of motion, motion graphs, measuring g with light gates, and projectile motion without air resistance.
Which unit are linear motion and dynamics examined in?
They are part of Unit AS 1: Forces, Energy and Electricity.
What is the key idea for projectile questions?
Split the motion into horizontal (constant velocity) and vertical (acceleration g), solve the vertical part for time, then use that time in the horizontal part.
