Question

When a driver presses the brake pedal, his car stops with an acceleration of -8.7 m/s2. How far will the car travel while coming to a complete stop if its initial speed was 10 m/s?

Answer 1

we are given with the initial velocity and the deceleration rate and is asked in the problem the distance the car travels until the car stops. we use the kinematic equation v 2 =v 0 2 +2aΔx where vo = 10 m/s , a = -8.7m/s^2 and v = 0

0 = 100 - 2* 8.7* Δx 
Δx  = 5.75 m. 

Answer 2

Answer:

5.74 m

Explanation:

We can solve the problem by using the following SUVAT equation:

$v^2 -u^2 =2aS$

where

v is the final velocity (in this case, v=0, since the driver comes to a stop)

u is the initial velocity (in this case, u=10 m/s)

a is the acceleration (in this case, a=-8.7 m/s^2)

S is the distance covered by the car

Re-arranging the equation and substituting the numbers given by the problem, we can find S:

$S=\frac{-u^2}{2a}=\frac{-(10 m/s)^2}{2(-8.7 m/s^2)}=5.74 m$