- #1

Johny Prime

- 12

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## Homework Statement

Having trouble with the concept here and have gotten stuck!

A man is pushing a mobile machine down a corridor at a steady speed of 1.2 m/s. The machine’s mass is 55 kg. Another person who has been walking in front of the machine has suddenly stopped. If the man is able to apply sufficient force to stop the machine in 1.0 s., will the man avoid a collision if the person is 1.0 m ahead of the machine? (Assume that the man is applying the same magnitude of force throughout that time.)

Velocity (initial) = 1.2 m/s

Mass = 55 kg

Velocity is at 0 after 1 second

Distance between is 1 meter

## Homework Equations

- Acceleration = (Vf-Vi)/time
- Force = acceleration X mass
- Velocity = Distance/time

## The Attempt at a Solution

Vf= 0 (stopped)

Vi= 1.2 m/s

So now finding the acceleration (deceleration): (0-1.2m/s)/1s = -1.2 m/s

^{2}

Can now find the force required to stop: Force = -1.2 X 55 kg

Force = -66 Newtons

This is where I am stuck. I am not sure if I am supposed to use : Force X Distance = 1/2 mv

^{2}formula (kinetic energy and work etc) or I am missing something obvious? If my work is correct so far what should be my next step?