**Goal:** Reasoning with energy

**Source:** UMPERG-ctqpe64

Two

masses, M > m, travel down the surfaces shown. Both surfaces are

frictionless. Which mass has the largest speed at the bottom?

- m
- M
- Both have the same speed
- Cannot be determined

**Goal:** Reasoning with energy

**Source:** UMPERG-ctqpe64

Two

masses, M > m, travel down the surfaces shown. Both surfaces are

frictionless. Which mass has the largest speed at the bottom?

- m
- M
- Both have the same speed
- Cannot be determined

## Commentary:

## Answer

(3) By energy considerations, both would have the same speed.

Students frequently get confused about the mass, thinking that the

larger mass has the greatest potential energy change and therefore has

the greatest speed.