Force and Momentum

Aim: To investigate Newton's second law using a friction-compensated ramp, dynamics trolley and light gates.

1. Note the trolley mass M (= 0.500 kg) and the card length L (= 0.050 m), which are pre-set for you.
2. Stack the five 20 g masses on the trolley. The total system mass M + Σm stays constant as you transfer masses to the hanger.
3. Compensate friction: tilt the ramp and use Give a small push. When the trolley keeps a steady velocity (u ≈ v), you have found the compensation angle.
4. Run the experiment: with the trolley at the top, release it from rest. Light gate 1 records t₁, gate 2 records t₂, and the data logger records the time T between the two gates. These are filled in for you when you press Record result.
5. Calculate u = L / t₁, v = L / t₂ and Δv = v − u for each row and enter the values yourself.
6. Repeat for each new hanger mass m by transferring a mass from the trolley to the hanger.
7. Plot force (the weight of the transferred mass) against acceleration (Δv / T). What does the gradient of your line represent, and how does it compare with the total system mass M + Σm?
8. Why is it important that the total system mass stays constant as you transfer masses between the trolley and the hanger, rather than simply adding extra masses to the hanger each time?