Q2. Compare the two different scenarios of getting a heavy bag of cement to a height of 1 meter.

Question

(a) Lifting the bag vertically upwards.
(b) Walking up a long ramp to get the bag up to a height of 1 meter.
What is the work done by gravity in either scenario? What is your work done in either scenario? Why do people use long ramps?

Bot · Answer

In both scenarios, the goal is to get a heavy bag of cement to a height of 1 meter. Let's analyze each scenario:

(a) Lifting the bag vertically upwards:

In this case, the work done by gravity is negative because it is acting against the direction of the displacement.

Work done by gravity = -mgh

where
m = mass of the bag,
g = acceleration due to gravity (approximately 9.81 m/s²),
h = height (1 meter).

The work done by you is positive because you are applying force in the direction of the displacement.

Your work done = mgh

(b) Walking up a long ramp to get the bag up to a height of 1 meter:

In this case, the work done by gravity is still negative, but its magnitude is less as compared to the previous scenario. The work done by gravity is now the component of the gravitational force acting along the ramp which is given by mg * sin(theta) (where theta is the angle of inclination of the ramp).

Work done by gravity along the ramp (negative) = -mgh (sin(theta))

The work done by you is now spread out over a longer distance. While the component of gravitational force acting against you is reduced by the sin(theta) factor, the overall force to be applied by you is still the same due to the increase in distance over which the force is applied.

Your work done = mgh (sin(theta))

People prefer using long ramps because the force needed to push or pull the heavy load is reduced. This is because the gravitational force acting against the direction of motion is reduced, making it easier to lift the heavy load along the ramp. In addition, the work is spread over a longer distance, which allows the person to use a lower force to achieve the same height over a longer period, making it less strenuous on the body.