Question

10. A car is moving in a straight line starts from rest, accelerates uniformly at 12 m/s2 for the first 5s, then travels at uniform speed for the next 2s and finally decelerates uniformly at 4 m/s2 for the next 5s. Draw the acceleration-time graph, velocity-time graphs and determine the distance travelled by the car during given time period.

Answer 1

d1 = 0.5a*t^2 = 0.5*12*5^2 = 150 m.
V1 = a*t = 12 * 5 = 60 m/s.

d2 = V*t = 60m/s * 2s = 120 m.

d3 = Vo*t + 0.5a*t^2
d3 = 60*5 - 0.5*4*5^2 = 250 m.

d = d1+d2+d3 = 150+120+250 = 520 m.