Mechanics Homework Help

About Mechanics

Mechanics is the physics of forces and motion: why things speed up, slow down, balance or fall over. It is the first substantial topic in most physics courses and the one that rewards drawing before calculating. The questions students bring here run from a block on an inclined plane and a man in a lift to speed-time graphs, pulleys, collisions and the work done lifting a bucket of water.

Popular topics in Mechanics

• Newton's Laws

  Resultant force and acceleration, action and reaction, normal reaction in a lift, and why a body moves at constant velocity.

• Motion & Graphs

  Velocity, acceleration, displacement, the equations of uniform acceleration, and reading distance-time and speed-time graphs.

• Work, Energy & Power

  Work done against gravity and friction, kinetic and potential energy, conservation of energy, and power as work per second.

• Momentum & Collisions

  Impulse, conservation of momentum, elastic and inelastic collisions, and the coefficient of restitution.

• Moments & Equilibrium

  The principle of moments, the centre of gravity, balancing a metre rule, and the conditions for equilibrium of coplanar forces.

• Friction & Inclined Planes

  Limiting friction, the coefficient of friction, and resolving weight along and perpendicular to a slope.

• Machines

  Pulleys and block-and-tackle systems, levers, the inclined plane, velocity ratio, mechanical advantage and efficiency.

• Projectiles & Circular Motion

  Horizontal and angled projection, time of flight and range, centripetal force, and motion in a vertical circle.

How ScanSolve helps with Mechanics

Photograph the question and ScanSolve starts where a physics teacher starts: identifying the body, the forces on it and the direction taken as positive. The free-body reasoning is written out before any number is substituted, because a sign error in mechanics almost always begins with an unlabelled diagram.

Each solution carries its units through the working rather than adding them at the end, states the formula being used, and checks the result for physical sense — a speed that exceeds the initial value after braking, or a tension larger than the weight, is flagged rather than left standing. For graph questions the answer explains what the gradient and the area under the line each represent.

Study tips for Mechanics

1. 01

   Draw the free-body diagram first, every time, and choose a positive direction before you write an equation. Most "careless" mechanics errors are direction errors.

2. 02

   Keep your units in the working. Substituting 20 g into a formula that expects kilograms is the single most common reason a correct method scores zero.

3. 03

   For a speed-time graph, remember what each feature means: the gradient is acceleration and the area under the line is distance. Many questions ask for nothing else.

4. 04

   Before you calculate, ask which quantity is conserved. If it is momentum, you rarely need energy; if energy is conserved, you rarely need the forces.

Frequently asked Mechanics questions

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