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, $a =  \frac{-825}{75}$

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

Answer:

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

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

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 $m/s^2$