Question

You carry a 7.0 kg bag of groceries above the level floor at a constant velocity of 75 cm/s across a room that is room. How much work do you do on the bag in the process?

Answer 1

Answer:

1.97J

Explanation:

Given parameters:

Mass of the groceries = 7kg

velocity of the bag = 75cm/s

Unknown:

Work done to move the bag  = ?

Solution:

Work done is the force applied to move a body through a distance in a specific direction:

     Work done = Force x distance

In this case, the work done is the kinetic energy applied in pulling the bag.

Kinetic energy is the energy in motion of a body.

 Work done  = kinetic energy = $\frac{1}{2} m v^{2}$

where m is the mass

           v is the velocity

Now, convert the velocity from cm/s to m/s

   100cm = 1m

 75$\frac{cm}{s }$  x $\frac{1m}{100cm}$  = 0.75m/s

 Work done  = $\frac{1}{2}$ x 7 x 0.75² = 1.97J