Question

In a science demonstration, 4 to 6 plastic bags are arranged under a 2.0 m × 2.0 m piece of plywood. A volunteer stands on the plywood and others blow into the bags to "levitate" the volunteer. If four bags are used and a 140-lb person is on the plywood, what is the pressure hat must be supplied by each of the four blowers (in Pa)? What if 6 bags and blowers were used? (Assume the plywood has no mass.)

A) 1.75Pa for 4 bags and 1.17Pa for 6 bags
B) 1.17Pa for 4 bags and 1.75Pa for 6 bags
C) 0.88Pa for 4 bags and 0.58Pa for 6 bags
D) 0.58Pa for 4 bags and 0.88Pa for 6 bags

Answer 1

To levitate a 140-lb person using four or six plastic bags, each blower must provide a pressure of 155.69 pascals (Pa). Provided options A-D do not match this calculated value, indicating a potential error in the options.

Step-by-step explanation:

To calculate the pressure that must be supplied by each of the four or six blowers, we first need to convert the weight of the person standing on the plywood into force, which we do by multiplying the weight in pounds (lb) by the gravitational constant 9.81 m/s² to get the force in newtons (N). We then divide this force by the number of bags to find out how much force each bag needs to support. Finally, we divide this force by the area over which this force is to be applied to find the pressure in pascals (Pa).

The area of the plywood is 2.0 m × 2.0 m, so the total area is 4.0 m². For four bags, the area per bag is 1.0 m², and for six bags, it is approximately 0.67 m².

First, we convert the volunteer's weight to newtons (N): 140 lb × 4.44822 N/lb = 622.75 N. Then we calculate the pressure:
For four bags: 622.75 N / 4 bags / 1.0 m² per bag = 155.69 Pa per bag.
For six bags: 622.75 N / 6 bags / 0.67 m² per bag = 155.69 Pa per bag.

As none of the options provided (A-D) match these calculations, there likely has been a misunderstanding or additional information is required to provide the correct answer. However, the calculated pressure of 155.69 Pa per blower for both four and six bags is the correct answer based on the information at hand.