A2L Item 131
- Description: Specify the motion of a block on an incline given that a block of half the mass moves with constant speed.
- Goal: Reasoning with dynamics
- Source: UMPERG-ctqpe30
- Keywords: Dynamics, Forces, Friction, Mechanics, Reasoning
The question for students:
A
block of mass m, when placed on a rough inclined plane and moved, moves
down the plane with constant speed. If a block of mass 2m were placed
on the same incline and moved, it would …
- return to rest.
- accelerate until the speed is half.
- move with some constant speed.
- None of the above.
- Cannot be determined
Commentary for teachers:
Answer
The block will have the same motion. Both the gravitational force and the friction force scale with the mass so there is no net force in either case.