Question

1. Explain interms of impulse how padding reduces forces in a collision State this interms of a real example, such as the advantages of a carpeted vs. tile floor for a day care center.

2. Since astronauts in orbit are apparently weightless, a clever method of measuring their masses is needed to monitor their mass gains or losses to adjust diets. One way to do this is to exert a known force on an astronauts and measure the acceleration produced. Suppose a net external force of 50.0 N is exerted and the astronaut's acceleration measured to be 0.893 m/s, (a) calculate her mass: (b) by exerting a force on the astronaut, the vehicle in which they orbit experiences an equal and opposite force. Discuss how this would affect the measurement of the astronaut's acceleration. Proposed a method in which recoil of the vehicle is avoided. Write your answers to the space provided below.

Answer 1

1. The padding increases the time it takes to hit the hard floor, decreasing the impulse, so, the person faces softer consequences.

2. (a) The mass:

$$m=\frac Fa=56\text{ kg}.$$

(b) This can decrease the value of measured acceleration because after applying the force, the vehicle can move in the opposite direction.

The method that allows measuring the astronaut's mass more precisely is to give the astronaut a gun that strikes a projectile of a known mass at known velocity. After the strike, the astronaut and the gun will move in the opposite direction. Measuring the speed of the astronaut with the gun relative to the vehicle and applying momentum conservation, we can find the mass.