Question

A person driving a car suddenly applies the brakes. The car takes 7.0 s to come to rest while traveling 26 m at constant acceleration. What was the initial speed of the car (in m/s)?

Answer 1

7.43 m/s

Step-by-step explanation:

Time taken for car to stop = 7.0 s

distance traveled before coming to rest = 26 m

Final speed of the car = 0 m/s (since it stops)

initial speed of the car = ?

To get the final speed, we use the equation

s =
`(1)/(2)t(u + v)`

where

s is the distance traveled before stopping

u is the initial speed = ?

v is the final speed = 0 m/s

t is the time = 7 s

substituting values, we have

26 =
`(1)/(2)*7*(u + 0)`

26 = 3.5u

u = 26/3.5 = 7.43 m/s