Question

A car is traveling at 50 ft/s when the driver notices a stop sign 100 ft ahead and steps on the brake. Assuming that the deceleration due to braking is constant, what is the magnitude of the minimum deceleration for which the car would stop right at the stop sign?

Answer 1

Answer:

minimum deceleration = 12.5 ft/s²

Explanation:

Data provided in the question:

Initial speed of the car, u  = 50 ft/s

Distance to cover, s = 100 ft

Final speed of the car = 0 ft/s             [ ∵ as the car stops ]

Now,

from the Newton's equation of motion

we have  

v² - u² = 2as

a is the acceleration

on substituting the respective values, we get

0² - 50² = 2 × a × 100

or

- 2500 = 200a

or

a = - 12.5 ft/s²

Here, the negative sign depicts the deceleration.