Mechanics
A-Level Mechanics
Mechanics models motion and forces: kinematics, Newton's laws, connected particles, projectiles and moments.
What you need to know
- The suvat equations for constant acceleration
- Newton's second law F = ma
- Resolving forces and friction
- Projectile motion with independent horizontal and vertical components
Key concepts
- Always draw a force diagram and define a positive direction first.
- Use g = 9.8 m s⁻² unless told otherwise.
- In projectile motion horizontal velocity is constant; vertical acceleration is −g.
Common mistakes
- Mixing up sign conventions between velocity and acceleration
- Using a suvat equation when acceleration is not constant
- Forgetting that tension is the same throughout a light inextensible string
Example question
A particle starts from rest and accelerates at 4 m s⁻² for 5 s. Find its final speed in m s⁻¹.
Show explanation
v = u + at = 0 + 4 × 5 = 20 m s⁻¹.
Practise Mechanics
4 original questions with worked explanations, mixed across easy, medium and challenging difficulty.
Mechanics questions students ask
- How accurate should my answers be?
- Give answers to three significant figures unless the question specifies otherwise, and keep full accuracy in intermediate working.