Calculating Work Done by a Lady Carrying Groceries

Understanding Work Done at Constant Velocity

A lady carries a 7.0kg bag of groceries 1.2m above the ground at a constant velocity across a 2.3m room. How much work does the lady do on the bag in the process?

Since the lady is carrying the bag of groceries at a constant velocity, the net force acting on the bag is zero, which means the work done by the lady on the bag is zero.

This is because work is defined as the product of the force and the displacement of an object in the direction of the force.

work = force x displacement x cos(Φ)

where Φ is the angle between the force and displacement vectors.

In this case, the force the lady exerts on the bag is upwards to counteract the force of gravity pulling the bag downwards, and the displacement is horizontally across the room.

Since the force and displacement vectors are perpendicular to each other, the angle theta between them is 90 degrees, and cos(theta) = 0.

Therefore, the work done by the lady on the bag is:

work = force x displacement x cos(theta) = 0 x 2.3 x 0 = 0

So the lady does no work on the bag as she carries it across the room at a constant velocity.

What is the work done by the lady on the bag of groceries as she carries it across the room at a constant velocity?

The work done by the lady on the bag of groceries is zero because the force she exerts to counteract gravity is perpendicular to the displacement of the bag, resulting in no work being done due to the angle between the force and displacement vectors.