Washer/Elevator Lab

Washer Lab:

• Observation: As we pull the washers at constant velocity, its weight is equivalent to its resting weight. When the washers, however, accelerates upward, its weight is greater than its resting weight. When the washers accelerates downward, its weight is smaller than its resting weight

Question: 1) When the scale was decelerating, the value of a is negative; whereas when the scale was accelerating, the value of a is positive.
2) The relationship between an object's mass m, its acceleration a, and the applied force F is F = ma.

Example: The toy car has a mass of 2kg. The car is accelerating with the acceleration of 2m/s^2. The applied force on the toy car is F = ma = (2kg)(2m/s^2) = 4 N.

3) If the air friction is negligible, a feather and a rock will hit the ground at the same time because free fall does not depend on the mass of an object.

4) As the force is held constant, mass of an object decreases will cause the acceleration increases because mass and acceleration have an inversely proportional relationship.

Elevator Lab:

Procedure: Record person's actual weight. Then record his weight as the elevator accelerates upward or downward.

Data: Person's mass: 179 lbs ~ 81.19 kg

Mass when elevator accelerates upward: 182 lbs ~ 82.55 kg

Mass when elevator accelerates downward: 176 lbs ~ 79.83 kg

Calculation: 

Upward: mg + ma = 82.55kg 

=> 81.19 ( -9.8 ms-2 + a) = 82.55

=> a = 10.82 ms-2

Downward: mg + ma = 79.83 kg

=> 81.19 ( 9.8 ms-s + a) = 79.83

=> a = -8.82 ms-2

Error Analysis: There will be slight errors in recording the person's weight.