A scene in a movie has a stuntman falling through a floor on

A scene in a movie has a stuntman falling through a floor onto a bed in the room below. The plan is to have the actor fall on his back, but you have been hired to investigate the safety of this stunt. When you examine the mattress, you see that It effectively has a spring constant of 65144 N/m for the area likely to be impacted by the stuntman, but cannot depress more than 11.35 cm without injuring him. To approach this problem, consider a simplified version of the situation. A mass falls through a heiaht of 3.92 m before landing on a spring of force constant 65144 N/m. Calculate the maximum mass that can rail on the mattress without exceeding the maximum compression distance. Based on this crude measurement, is the stunt safe using the proposed mattress? Warning: The safety of movie stunts is now heavily researched and involves more sophisticated computations than used hero. Do not attempt stunts on your own.

Solution

a)

By Conservation of energy

PE=KE

mg(h+x) =(1/2)kx²

m*9.8*(3.92+0.1135) =(1/2)*65144*0.1135²

m = 10.6 Kg

b)

Answer is no ,sice the mass of stunt man will be more than 10.6 Kg