A-Level Physics: Forces, Energy and Materials

This quiz spans the second half of A-Level mechanics — Newton's laws, momentum, energy — and the materials content that extends it into stress, strain and the Young modulus. These are the topics where multi-step calculations dominate the paper, and every question here is built as one.

The Newton's-laws questions apply the machinery to real configurations: the normal force on an inclined block (resolved with cosine), and the connected-masses-over-a-pulley problem whose answer key was independently recomputed and corrected during verification — the weight difference drives the whole five-kilogram system, giving 1.96 m/s², not the double-counted value the original key carried. Momentum appears twice: a bouncing-ball impulse problem where the rebound reverses the velocity sign, and a perfectly inelastic collision solved by conservation with opposite-direction velocities handled correctly.

The energy questions cover conservation scenarios (which situations genuinely conserve mechanical energy), the work-energy-power relationships as statements to evaluate, and density in a routine mass-from-volume calculation.

The materials questions apply the definitions with real numbers: Hooke's law proportionality scaled from one force-extension pair to another, elastic strain energy as ½kx², and a full stress-strain-Young-modulus problem — stress of 5.0 × 10⁷ Pa, strain of 0.002, modulus of 2.5 × 10¹⁰ Pa — whose distractors encode precisely the extension-versus-strain confusion the verification pass confirmed students (and even the automated solver) fall into.

All values are given in the questions, consistent with the exam's data booklet, and the explanations carry the complete numeric chain from substitution to answer.

• Apply Newton's laws to inclined planes and connected-particle systems
• Use impulse and conservation of momentum, handling direction signs correctly
• Evaluate when mechanical energy is conserved and apply work-energy-power relations
• Scale forces and extensions with Hooke's law and compute elastic strain energy
• Work stress, strain and the Young modulus from raw dimensions and loads

Topic scope follows sections 3.4.1-3.4.2 of the current A-level physics subject content: Newton's laws, momentum and impulse, work, energy and power, density, Hooke's law, and the stress-strain properties of materials including the Young modulus.