A school has organise an athletic competition which instruments are suitable to time each of the following activities; 100 meters race 20000 meters race?

For timing the 100 meters race, a stopwatch or electronic timing system would be suitable. For the 20000 meters race, a timing system with a lap counter or a GPS tracking device would be more appropriate to accurately measure the longer distance.

100 meters race:

- Photo finish camera
- Laser timing system
- Electronic timing gates

20000 meters race (20 km):

- Stopwatch
- GPS tracking device
- Chip timing system (transponders)