You are lifting a 15 kg weight. You lift the bar 0.25 m a total of 15 times. a. What is the total height the bar was lifted?

b. What is the force needed?

c. What is the work done?

Explanation:

Given parameters:

Mass of the weight  = 15kg

Height of bar lift  = 0.25m

Number of times lifted  = 15times

Unknown:

Total height the bar was lifted  = ?

Force needed for the lift = ?

Work done  = ?

Solution:

To solve this problem we need to understand that;

        Work done  = Force x distance

         Work done = mass x acceleration due gravity  x height

         Work done  = weight x height

a. Total height:

   Total height  = 0.25 x 15  = 3.75m

b. Force needed ;

   Force needed  = Weight of bar  = mass x gravity

                                                        = 15 x 9.8 = 147N

 So;

    Force used for the 15 times  = 15 x 147  = 2205N

c. Work done ;

      Work done  = weight x height  = 2205 x 3.75  = 8268.75J