Edexcel International A Level Physics Mechanics Exam Questions

About Edexcel International A Level Physics Mechanics

Mechanics is the main part of Unit 1: Mechanics and Materials in Edexcel International A Level Physics. It covers motion in one and two dimensions using the equations of uniformly accelerated motion and motion graphs, resolving vectors, projectile motion and Newton's three laws. You also use momentum and its conservation in one dimension, moments and equilibrium, and work, energy, power and efficiency. Mechanics is extended in Unit 4 (Further mechanics). Examiners often set free-body force diagram questions, projectile calculations and energy conservation problems, and expect clear working with correct units.

What you need to know

• Kinematics Use v = u + at, s = ut + ½at^2, v^2 = u^2 + 2as and s = ½(u + v)t for uniform acceleration. Interpret displacement-time, velocity-time and acceleration-time graphs.
• Vectors and projectiles Add vectors and resolve them into perpendicular components. For projectiles, horizontal velocity is constant and vertical motion has acceleration g.
• Newton's laws ΣF = ma; weight W = mg; Newton's third law pairs are equal, opposite, of the same type and act on different bodies.
• Momentum p = mv. In a closed system, total momentum is conserved in one dimension.
• Moments Moment = Fx (perpendicular distance). In equilibrium, the resultant force and the resultant moment are both zero. The weight acts at the centre of gravity.
• Work, energy and power ΔW = FΔs, ΔEgrav = mgΔh, Ek = ½mv^2, P = ΔW/Δt, and efficiency = useful output/total input.

Common mistakes in Mechanics

• Using SUVAT equations when acceleration is not constant.
• Using the speed at the top of a projectile's flight as zero instead of only the vertical component.
• Naming weight and normal reaction as a Newton's third law pair.
• Forgetting to include the weight of a beam in moments problems.
• Ignoring the sign of velocity in momentum calculations.

Try three Mechanics exam-style questions