A2L Item 084
- Description: Identify which of two masses that slide down an inclines with friction has the larger speed at the bottom.
- Goal: Reasoning with dynamics.
- Source: UMPERG
- Keywords: Acceleration, Forces, Friction, Mechanics
The question for students:
Two masses (M > m) are on an incline. Both surfaces have the same coefficient of kinetic friction. Both objects start from rest, at the same height. Which mass has the largest speed at the bottom?
- m
- M
- Both have the same speed.
- Cannot be determined
Commentary for teachers:
Answer
(3) Both will have the same speed. All the forces acting on the mass (normal, friction, gravity) are proportional to the mass so the mass cannot affect the acceleration experienced by the mass.