Question

The velocity of a solar powered car as a function of time. The driver accelerates from a stop sign. Cruises for 20s at a constant speed of 60km/hr and then brakes to come to a stop 40s after leaving the stop sign

a) Compare the average acceleration during the following time intervals

i) t=0 to t=10s;

ii) t= 30s to t=40s

iii) t=10 to t= 30s

iv) t=0 to t=40s

b) what is the instantaneous acceleration at t = 20s and t=35s ?

Answer 1

a) i)

$$a=\frac{60}{3.6\cdot 10}=1.67\frac{m}{s^2}$$

ii)

$$a=\frac{0-60}{3.6\cdot 10}=-1.67\frac{m}{s^2}$$

iii)

$$a=0\frac{m}{s^2}$$

iv)

$$a=\frac{0-0}{40}=0\frac{m}{s^2}$$

b)

$$a(20)=0\frac{m}{s^2}$$

$$a(35)=-1.67\frac{m}{s^2}$$