Question

During a crash test, an air bag inflates to stop a dummy’s forward motion. The dummy’s mass is 75kg. If the net force on the dummy is 825 N toward the rear of the car, what is the dummy’s acceleration?

Answer 1

Mass of the dummy m = 75 kg

Net Force on the dummy
`F_(net)  = -825 N` since it is given that the force is towards the backside of the car.

Acceleration of the dummy a = ?

Using Newton's 2nd law of motion, we have

`F_(net)  = ma`

-825 = (75)a

Hence,
`a =  (-825)/(75)`

Acceleration of the dummy is -11
`m/s^(2)`

The negative sign indicates that the dummy is slowing at a rate of 11
`m/s^(2)`

Answer 2

Acceleration towards rear = 11
`m/s^2`

Acceleration towards direction of movement of dummy = -11
`m/s^2`

Step-by-step explanation:

Mass of dummy = 75 kg

Force acted towards rear of the car = 825 N

We have Force acting on a body = Mass of body * Acceleration of body

Substituting the given values in the above equation we will get

825 = 75 * a

a = 11
`m/s^2`

So acceleration towards rear = 11
`m/s^2`

Acceleration towards direction of movement of dummy = -11
`m/s^2`