Physics · 1.5.1 Forces & Newton's laws · Paper 6 practical
Newton's 2nd Law. Accelerate it.
Pull a trolley with a falling mass and measure its acceleration. Vary the force (keeping mass constant) to show a ∝ F; vary the mass (keeping force constant) to show a ∝ 1/m. Together: F = ma.
0625 Topic 1.5.1 — F = ma
Topic 1.2 — Acceleration
Paper 6 — ATP
0.00 s
v 0.00 m/s · a 0.00 m/s²
Shortcuts Space release · Enter record · R reset.
Variables
2.0
1.0
0.10
Live readouts
Net force F − friction
1.90 N
Total mass moved
1.00 kg
Acceleration a = F/m
1.90 m/s²
Velocity v
0.00 m/s
Newton's 2nd law: resultant force = mass × acceleration. Subtract friction from the driving force.
Trial data
Release the trolley and record runs at different F or m.
a vs F — gradient = 1/m
📋 Method (Cambridge ATP procedure)
- Set up a trolley on a runway connected over a pulley to a hanging mass; compensate for friction by tilting slightly.
- Use light gates (or a ticker-timer) to measure the trolley's acceleration.
- Keep total mass constant; vary the driving force by moving masses from the trolley to the hanger. Measure a for each F.
- Then keep the force constant and add masses to the trolley; measure a for each mass.
Analytical control: plot a against F (straight line through origin → a ∝ F, gradient = 1/m); plot a against 1/m (straight line → a ∝ 1/m).
⚠ Sources of error & precautions
- Friction — compensate by tilting the runway until the trolley moves at constant velocity when given a push.
- Total mass — when varying force, move masses between trolley and hanger so the total accelerated mass stays constant.
- Timing — use light gates rather than a stopwatch to reduce reaction-time error.
- Straight runway and the string parallel to the runway.
🎯 Syllabus reference (0625)
- 1.5.1 Forces — recall and use F = ma; recall that an unbalanced force causes acceleration; describe an experiment to investigate the relationship between force, mass and acceleration.
- 1.2 Motion — define and calculate acceleration; interpret speed–time graphs.