Answer to Question #128736 in Physics for Mbali

Question

A car of mass 1000kg accelerates from rest for 90s in a straight line to reach a sped of 59km/h. After that, it accelerates uniformly at 6m/s^2 for a further 30s.

a) Calculate the speed of the car at the end of the 30s period.
b) Calculate the total distance covered by the car.

Answer 1

(a)

$$v_f=v_i+at$$

$$v_f=59\times \frac{1000\:\rm m}{3600\:\rm s}+6\:\rm m/s^2\times 30\: s=196.4\:\rm m/s$$

(b)

$$d=d_1+d_2\\ =\frac{0+59\times \frac{1000\:\rm m}{3600\:\rm s}}{2}\times 90+\frac{59\times \frac{1000\:\rm m}{3600\:\rm s}+196.4\:\rm m/s}{2}\times 30\\ =3929\:\rm m$$