Q1.
Apart from force, does acceleration depends on any other factor? From everyday experiences, you know that with the same magnitude of force, it is easier to set lighter objects in motion than heavier ones. This leads to a second hypothesis, that for the same force, a smaller mass has a larger acceleration (or a larger mass has a smaller acceleration). Now how can you test your second hypothesis?
Answer
Run the same experiment again, but this time hold the force constant and change the mass of the cart.
- Repeat Activity 6.3 with one change: keep the mass of the cup and the objects in it constant, so the pulling force stays the same.
- Double the mass of the cart by adding objects inside it, and measure that mass on a weighing scale.
- Record the time over the same distance s, exactly as before, from the slow-motion video.
- Use a2 ÷ a1 = T12 ÷ T22 to compare the two accelerations.
Why this design works: a hypothesis about mass can only be tested if mass is the only thing you change. The force (weight of the cup and its contents), the surface, the starting velocity u = 0 and the distance s are all kept fixed, so any change in the timing must come from the change in mass. This is the same "change one variable at a time" logic that made Activity 6.3 a fair test of force.