Question

- A car traveling at 60 m/s began to decelerate with 1.5 m/s2
. Calculate the required time for the car to move a distance of 70 m during its slow down.

Answer 1

Answer:

40 ± 2√(3390)/3

Explanation:

u = 60m/s

a = - 1.5m/s^2

To find:

Time to cover 70m in deceleration.

Formula:

s = ut + 1/2 at^2 ( Newton's second law of motion)

Solution:

70 = 60t + 1/2 * -1.5t^2

70 = 60t - 0.75t^2

0.75t^2 - 60t + 70 =0

Using quadratic formula we get

Roots: 78.815804341359, 1.184195658641

Root Pair: 40 ± 2√(3390)/3

t = 40 ± 2√(3390)/3

I think this question is incorrect as we get 2 value of t which are valid