b) Finding total distance :
Distance travelled from 0 s to 5 s :
- 1/2 x 5 x 30 = 75 m
Distance travelled from 5 s to 10 s :
- 5 x 30 = 150 m
Distance travelled from 10 s to 15 s :
- 150 + 1/2 x 5 x 5
- 150 + 12.5 = 162.5 m
Distance travelled from 15 s to 20 s :
- 36 x 5 + 1/2 x 5 x 4
- 180 + 10 = 190 m
Distance travelled from 20 s to 25 s :
- 45 x 5 + 1/2 x 5 x 5
- 225 + 12.5 = 237.5 m
Distance travelled from 25 s to 30 s :
- 40 x 5 + 1/2 x 10 x 5
- 200 + 25 = 225 m
Distance travelled from 30 s to 35 s :
- 20 x 5 + 1/2 x 20 x 5
- 100 + 50 = 150 m
Distance travelled from 35 s to 40 s :
- 1/2 x 20 x 5
- 50 m
Total = 75 + 150 + 162.5 + 190 + 237.5 + 225 + 150 + 50
Total = 1240 m
c) velocity at t = 15 s
- 36/15
- 12/5
- 2.4 m/s
d) average velocity
- 0 m/s (as displacement is equal to 0)
e) average speed
- 1240/40
- 31 m/s
f) Part d uses displacement whereas part e uses distance