In a science demonstration, 4 to 6 plastic garbage bags are arranged under a 2 m by 2 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 that 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).
Pressure = 140/4m^2. The number of bags has no influence, in any case, the pressure above is needed to move the plank.
39 Pa for each of 4 blowers; 26 Pa for each of 6
To calculate the pressure that must be supplied by each of the four blowers, we can use the formula:
Pressure = Force / Area
In this case, the force is the weight of the person, which is 140 lbs. We need to convert this weight to Newtons (N) because the unit of pressure, Pascal (Pa), is derived from the unit of force, N.
We know that 1 lb is approximately equal to 4.448 N, so we can convert the weight of the person:
Weight = 140 lbs * 4.448 N/lb
Weight = 621.52 N
Next, we need to calculate the area of the plywood. The plywood is a square with sides measuring 2 m, so the area is:
Area = Side length * Side length
Area = 2 m * 2 m
Area = 4 m^2
Now let's calculate the pressure required with 4 bags:
Pressure = Weight / Area
Pressure = 621.52 N / 4 m^2
Pressure = 155.38 Pa
Therefore, each of the four blowers must supply a pressure of approximately 155.38 Pa.
If we were to use 6 bags instead, the pressure required would still be the same because the number of bags does not influence the force required. So the pressure required with 6 bags would also be approximately 155.38 Pa.