Answer:
8.98 secs
Explanation:
First part of the journey;
If the car starts from rest, then accelerates at 1.20 m/s^2 for 7.00 s, the total time taken during this period is 7.0s.
But then lets get the velocity v of the car during its first part of the journey.
Using the formula v1 = u1+ at1
v = 0+1.2(7)
v = 8.4m/s
Second part of the journey is when the driver hits the brake and slowing to stop at a rate of -4.25 m/s^2. To calculate the time it takes by the body to decelerates, we will use the equation of motion v2 = u2 + at2
v = final velocity of the car during the second part of the journey
u = initial velocity of the car during the second part of the journey
a = deceleration
t = time taken
Given v2 = 0m/s, u2 = 8.4m/s, a = -4.25m/s²
0 = 8.4-4.25t2
4.25t2 = 8.4
t2 = 8.4/4.25
t2 = 1.98secs
Total time taken for the journey = t1+t2
= 7.0s + 1.98s
= 8.98secs
