Hello,

I need help with a question on Variable Acceleration in Mechanics,

The question is: A car starts from rest and travels along a straight road. Its speed, v ms^-1, at time t seconds is modelled by:

v=4t-0.2t^2, 0 <= t <= 10,

v=constant, 10 <= t <= 15,

v=8+0.8t, t => 15.

i) Calculate the speed of the car at t=0, t=10, t=15 and t=20.

ii) Find the values of the acceleration at

A) t=7,

B) t=12,

C) t=16.

iii) Calculate the distance the car travels in the interval 10 <= t <= 20.

iv) Calculate the distance the car travels in the interval 0 <= t <= 10.

I have worked out the first two questions, but do not know how to do part (iii)

Thank you.