a bus moves from rest with a uniform acceleration of 2ms² for the

a bus moves from rest with a uniform acceleration of 2ms² for the first 10 seconds. it then accelerate at a uniform rate of 1ms² for another 15seconds. it continues at a constant speed for 70seconds and finally came to rest in 20seconds by uniform acceleration, calculate the average speed for the whole journey.

3 answers

since
v = at and
s = vt + 1/2 at^2 for each section,
total distance: (1/2 * 2 * 10^2) + (2*10*15 + 1/2 * 1 * 15^2) + (2*10 + 1*15)*70 + (2*10 + 1*15)*20 - 1/2 (35/20) * 20^2

avg speed is then totaldistance / totaltime

2m/s2 And 16m/s

20m