**Goal:** Problem solving with kinematics

**Source:** CT151.2-4

Ann is running with a constant speed of 3 m/s on a straight track. Deb

is also running with constant speed but is initially 10 m behind Ann. If

Deb catches up to Ann after Deb has traveled 55 m, how fast is Deb

running?

- 3.2 m/s
- 3.55 m/s
- 3.75 m/s
- 4.15 m/s
- More than 4.2 m/s
- none of the above
- cannot be determined

## Commentary:

## Answer

(6) The correct speed is 3.67 m/s. Students indicating #2 or #3

are likely making an arithmetic error. Have students graph the position

vs. time graphs for each runner.