Bart runs up a 2.91 meters high flight of stairs at a constant speed in 2.15 seconds. If barts mass is 65.9kg determine the work which he did and his power rating

1879.33J

874.1W

Explanation:

Given parameters:

Distance covered  = 2.91m

Time taken  = 2.15s

Mass of Bart = 65.9kg

Unknown:

Work done  = ?

Power rating  = ?

Solution:

Here, the work done is related to the the potential energy in climbing this flight of stairs.

  Work done = Potential energy  = mgH

where m is the mass

           g is the acceleration due to gravity

           H is the height

Work done  = 65.9 x 9.8 x 2.91  = 1879.33J

Power is defined as the rate at which work is being done.

         Power =

                     =

                      = 874.1W

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.