Chapter 6, Problem 62A

An occupant of a car can survive a crash if the deceleration during the crash is less than 30g. Calculate the force on a 70-kg person decelerating at this rate.

To determine

Force on the person.

Answer to Problem 62A

Force is equal to, $F=20580\text{ N}$ .

Explanation of Solution

Given:

Mass of the person, $m=70\text{ kg}$

Deceleration is, $a=30g{\text{ m/s}}^2$

Formula used:

According to Newton’s law.

  $F=ma$

Where, m is mass and a is acceleration.

Calculation:

Acceleration due to gravity is, $g=9.8{\text{ m/s}}^2$

Therefore, deceleration of person is,

  $\begin{array}{l}a=30\times 9.8\\ =294{\text{ m/s}}^2\end{array}$

Now, substituting the value of m and a and solve.

  $\begin{array}{l}F=70\times 294\\ =20580\text{ N}\end{array}$

Conclusion:

Therefore, force applied on the person is 20580 N.