Question

Kathy is running a 100 m race. When the starter’s pistol fires, she leaves the starting block and continues speeding up until 4 s into the race, when she reaches her top speed of 9 m/s. She holds this speed for 5 s; then her speed has slowed to 7 m/s by the time she crosses the finish line 12 s after she started the race. The data for the race is presented in table below.

Time (sec)	Velocity (m/s)
0	0
4	9
6	9
9	9
12	7

1. Provide a sketch of the velocity vs. time graph for Kathy’s race. LABEL your axes clearly.

2. WhatwasKathy’saccelerationduringthefirst4softherace?

3. What was Kathy’s acceleration from 4 to 9 s into the race?

4. What was Kathy’s average velocity for the whole race?

5. What was Kathy’s decceleration from 9 to 12 s into the race?

Answer 1