GCSE Physics: Forces — Deep Revision Workbook

Inside GCSE Physics: Forces — Deep Revision Workbook

sort scalars from vectors and calculate weight with W = m × g, work through speed, velocity and acceleration with a = Δv ÷ t and read distance–time and velocity–time graphs (gradient and area), apply Newton's three laws with F = m × a, find resultant forces and use W = F × s and F = k × e, then master stopping distance and momentum p = m × v before a full exam-style challenge. About 45 minutes.

Learning objectives

• scalars and vectors and the difference between contact and non-contact forces, plus weight with W = m × g used both ways;
• motion — distance and displacement, speed and velocity, acceleration a = Δv ÷ t, and reading distance–time and velocity–time graphs, including the area under the line;
• Newton's three laws, resultant and free-body forces, and Newton's second law F = m × a;
• work done W = F × s and elasticity with Hooke's law F = k × e;
• stopping distance (thinking + braking distance and the factors affecting each) and momentum p = m × v.

Activities in this book

1. Section 1 — Scalars, Vectors, Force Types & Weight

   a scalar has magnitude (size) only — mass, speed, distance, energy, time. A vector has magnitude and direction — force, weight, velocity, acceleration, momentum. Contact forces need surfaces touching (friction, air resistance, tension, normal contact); non-contact forces act at a distance (gravitational, magnetic, electrostatic). Weight W = m × g. Use g = 10 N/kg here, so rearrange to m = W ÷ g when you need the mass.

2. Section 2 — Speed, Velocity, Acceleration & Graphs

   distance is a scalar; displacement is the vector version (straight-line distance plus direction). Speed is a scalar; velocity is speed in a stated direction. Speed = distance ÷ time. Acceleration a = Δv ÷ t in m/s². On a distance–time graph the gradient is the speed. On a velocity–time graph the gradient is the acceleration and the area under the line is the distance travelled.

3. Section 3 — Newton's Laws, Resultant Force, Work & Elasticity

   the resultant force is the single force left after adding forces along a line (same direction add, opposite subtract). Newton's 1st law: velocity stays constant unless a resultant force acts. Newton's 2nd law: F = m × a. Newton's 3rd law: every action has an equal and opposite reaction. Work done W = F × s in joules. Hooke's law F = k × e up to the limit of proportionality.

4. Section 4 — Stopping Distance & Momentum

   stopping distance = thinking distance + braking distance. Thinking distance grows with reaction time (tiredness, alcohol, drugs, distractions) and with speed; braking distance grows with speed, and with a wet or icy road, worn tyres or worn brakes. Momentum p = m × v (kg m/s) is a vector and is conserved in collisions. Rearrange to m = p ÷ v or v = p ÷ m.

5. Section 5 — Extended Exam-Style Forces Challenge

   exam questions reward joined-up physics: quote the equation, substitute with units, then explain the idea in words. For a 6-mark question, plan five or six clear points, use the correct key terms, and answer every part of the question.

Suggestions for teaching

• Equations first. Get learners to write the equation, substitute the numbers with units, then calculate — and to rearrange for the missing quantity.
• Vectors vs scalars. Keep sorting quantities into scalar (size only) and vector (size and direction) until it is automatic.
• Read the graphs. Drill that a distance–time gradient gives speed, while a velocity–time gradient gives acceleration and the area gives distance.
• Free-body thinking. Model resultant force and terminal velocity with weight down and air resistance up, so learners can explain motion in words.
• Momentum and safety. Link p = m × v to crumple zones and seat belts — a longer stopping time means a smaller force.