Mechanics & materials

By definition, simple harmonic motion is characterized by an accelerating force that is directly proportional to displacement but acts in the opposite direction, pulling the object back toward equilibrium. Option A is incorrect because the acceleration varies continuously as the displacement changes, meaning it cannot remain constant.

Momentum is conserved during the inelastic collision, so the initial momentum of 10 kg m/s must equal the final combined mass of 5 kg multiplied by the final velocity, yielding 2 m/s. Option C is incorrect because simply averaging the speeds ignores the fact that the stationary object has a larger mass.

Using the kinematic equation v^2 = u^2 + 2as, where final velocity v is 0, initial velocity u is 20 m/s, and acceleration a is -10 m/s^2, the maximum height s equals 20 m. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Option C is incorrect because simply averaging the speeds ignores the fact that the stationary object has a larger mass.
• !Option A is incorrect because the acceleration varies continuously as the displacement changes, meaning it cannot remain constant.

Answer each from memory — you'll see instantly whether you're right and why.

Run a focused 10-question mini-mock on Mechanics & materials and see it stick.