Which equation...?

Question

Will let me find force used in bringing an object to rest if I have its mass, velocity, and time that it comes to a stop in.

For example, If a 1000 kg car is sent tward a wall with a speed of 14 m/s and the impact brings it to a stop in 8 x 10^-2 s, what is the average force that brings it to rest?

Answer 1

Use Newton's 2nd Law of Motion, i.e.,

F = ma

where

F =  stopping force that brings the car to rest

m = mass of the car = 1000 kg.

a = acceleration of the car = v/t

v = velocity of car = 14m/sec. (given)

t = stopping time = 0.008 sec (given)

Substituting appropriate values,

F = (1000)(14/0.08)

F =  175,000 Newtons

Answer 2

use F = ma and

a = ΔV/Δt

a = 14m/s/.08s = 175 m/s²

F= 1000*175 = 175000N

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