Now, how can you test your hypothesis? You will have to think of an activity where you can apply forces of different magnitudes on the same object and the same surface to find the resultant acceleration. How can you apply forces of different magnitudes?

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Accepted Answer

Use weights of different magnitudes as the source of the force — the Earth pulls a heavier hanging load with a larger gravitational force. Weight of the hanging load, F = mg Double the mass in the cup → double its weight → double the pulling force on the cart Keep the cart, the surface and the distance travelled the same, so only the force changes The design of the test (Activity 6.3): Make a cart with ball-bearing wheels and tie a thread to it. Pass the thread over a pipe acting as a pulley at the edge of the table, and hang a paper cup from the free end. Put objects in the cup. As the cup falls, the thread pulls the cart with a constant force equal to the weight of the cup and its contents. Time the cart over a fixed distance s using a slow-motion video — call it T 1 . Double the mass in the cup (so the force doubles) and time it again — T 2 . Why this is a fair test: the mass of the cart, the surface, the starting velocity (u = 0) and the distance s are all held constant. The only thing changed is the pulling force, so any change in the acceleration must be caused by the force alone. That is exactly what a hypothesis about force and acceleration needs. cart cup + coins thread pulley same distance s in every trial The cart-and-pulley set-up. The weight of the cup and its contents supplies a constant, known-to-be-doubled pulling force.

NCERT Solutions for Class 9th Science Chapter 6 .5 Newton's Second Law of Motion — Think as a Scientist