Free Effects of forces questions for IGCSE Physics (0625), part of Motion, forces & energy. Each question has the answer and the marking points an examiner would look for.
Generate a full Effects of Forces worksheet →All Motion, forces & energy questionsAn object moves in a circle at constant speed.
Which statement is correct?
Answer: C
A spring has a spring constant of 20 N/m. It is stretched by 4.0 cm. What is the force on the spring?
Answer: B
A parachutist falls at terminal velocity and then opens her parachute.
Describe the forces acting at terminal velocity.
Explain what happens to her speed when she opens the parachute.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | weight = air resistance weight downwards and air resistance upwards B1 they are equal so the resultant force is zero B1 | 2 |
| (b) | air resistance increases, decelerates, new lower terminal velocity air resistance increases (larger area) B1 resultant force is upwards, so she decelerates B1 until a new, lower terminal velocity is reached B1 | 3 |
A student loads a spring with masses and measures its length.
Describe how she finds the extension.
Sketch and describe the load–extension graph if the limit of proportionality is exceeded.
State one precaution to make the length readings accurate.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | length minus original length measure the original (unstretched) length B1 extension = new length − original length B1 | 2 |
| (b) | straight line through origin then curves straight line through the origin B1 curving (becoming less steep) after the limit of proportionality B1 | 2 |
| (c) | eye level; pointer; ruler vertical read the ruler at eye level / use a pointer / keep the ruler vertical next to the spring B1 | 1 |
A skydiver of mass 75 kg jumps from a hovering helicopter.
Calculate the weight of the skydiver.
State the acceleration of the skydiver at the instant she jumps, and explain why.
Explain why her acceleration decreases as she falls, and why she reaches a terminal velocity.
When she is falling at a speed where the air resistance is 441 N, calculate her acceleration.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | 735 N W = mg = 75 × 9.8 C1 735 N A1 | 2 |
| (b) | 9.8 m/s²; only force is weight (no air resistance yet) 9.8 m/s² (g) B1 the only force acting is her weight since air resistance is zero when speed is zero B1 | 2 |
| (c) | air resistance increases with speed; resultant force decreases; forces balance at terminal velocity air resistance increases as speed increases B1 resultant (downward) force decreases so acceleration decreases B1 when air resistance equals weight the resultant force is zero and speed is constant B1 | 3 |
| (d) | 3.92 m/s² resultant force = 735 − 441 = 294 N C1 a = F/m C1 3.92 m/s² A1 | 3 |
A student hangs loads from a spring and measures the extension.
| load / N | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|---|
| extension / cm | 0.0 | 2.0 | 4.0 | 6.0 | 8.0 | 10.0 | 13.2 |
State Hooke’s law.
Use the table to suggest a value for the load at the limit of proportionality. Explain how you decided.
Calculate the spring constant of the spring, in N/m.
Predict the extension when a load of 3.5 N is hung on the spring.
Describe how the student should measure the extension accurately with a metre rule.
| Part | Answer and marking points | Marks |
|---|---|---|
| (a) | extension proportional to load (up to the limit of proportionality) extension is directly proportional to the load, up to the limit of proportionality B1 | 1 |
| (b) | 5 N (between 5 N and 6 N) 5 N, or between 5 N and 6 N B1 extension is proportional up to 5 N, but from 5 N to 6 N it increases by more than 2.0 cm B1 | 2 |
| (c) | 50 N/m k = F/x using a pair of values within the proportional region, with x in m, e.g. 5 ÷ 0.100 C1 50 N/m (allow 0.5 N/cm for C1 only) A1 | 2 |
| (d) | 7.00 cm 7.00 cm B1 | 1 |
| (e) | eye level with pointer; measure from a fixed pointer, subtract original length read the scale at eye level with the pointer (avoid parallax) B1 extension = new length − original length / use a fixed pointer on the spring B1 | 2 |
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Meet Riyaz →Original Cambridge-style practice questions written for mentorriyaz.in. These are not Cambridge past paper questions, and this site is not affiliated with or endorsed by Cambridge University Press & Assessment. Updated 2026-11-04. Paper generator · mentorriyaz.in