# Calculate the maximum mass that can fall on the mattress without exceeding the maximum compression distance.?

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 77144 N/m for the area likely to be impacted by the stuntman, but cannot depress more than 12.89 cm without injuring him. To approach this problem, consider a simplified version of the situation. A mass falls through a height of 3.32 m before landing on a spring of force constant 77144 N/m. Calculate the maximum mass that can fall on the mattress without exceeding the maximum compression distance.

### 1 Answer

- NCSLv 74 years agoFavorite Answer
GPE becomes SPE

mg(h+x) = ½kx²

M * 9.8m/s² * (3.32 + 0.1289)m = ½ * 77144N/m * (0.1289m)²

M = 19.0 kg

Hope this helps!