A 92.5 kg stunt man stands on a piston that will launch him out of a vertical tube. The piston applies a constant force F to the man's feet. Starting from rest, the force is applied for 1.20 s, and during that time interval, the man attains a velocity of 25.5 m/s. What was the man's apparent weight during this time interval?
A) Unable to answer without knowing the value of F.
B) 3740 N
C) 1970 N
D) 2830 N
E) 2870 N

Question

Quizplus · Accepted Answer

The apparent weight is the normal force exerted by the piston, which is the sum of the gravitational force and the force due to acceleration. Calculate acceleration using $ a = \frac{\Delta v}{\Delta t} = \frac{25.5 \, \text{m/s}}{1.20 \, \text{s}} = 21.25 \, \text{m/s}^2 $. The net force is $ F_{\text{net}} = ma = 92.5 \, \text{kg} \times 21.25 \, \text{m/s}^2 = 1965.625 \, \text{N} $. The gravitational force is $ F_g = mg = 92.5 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 906.5 \, \text{N} $. The apparent weight is $ F_{\text{apparent}} = F_{\text{net}} + F_g = 1965.625 \, \text{N} + 906.5 \, \text{N} = 2872.125 \, \text{N} \approx 2870 \, \text{N} $.

A 925 Kg Stunt Man Stands on a Piston That Will