Question

PLEASe someone help me with cal problem!! ...?

A car is traveling at 50 mi/h when the brakes are fully applied, producing a constant deceleration of 44 ft/s2. What is the distance covered before the car comes to a stop? (Give your answers correct to one decimal place.)

Answer 1

Since we are given a deceleration with a unit of ft/s2, it is convenient to convert 50 mi/h to ft/s. Appropriate conversion factors can be seen in the internet or in books.

50 mi/h = 73.33 ft/s

the equation for the distance travelled is

x = Vo*t - 0.5*a*t^2

where

x = distance travelled
Vo = initial velocity
t = time of travel
a = deceleration

since the time of travel is not known, we can find this using the equation

V = Vo - at

where V is the final velocity equal to zero (comes to stop)
substiruting values we get t = 1.67 s

therefore

x = 61.1 ft (0.01 mi)