Work and Kinetic Energy

Why are they clapping he did not do work

K.E is a scalar QuantityK.E Can not be NegativeK.E is measured by Joule (J)

Work

Work is energy transferred to or froman object by means of force acting

on the object

Work is said to be positive if transferred tothe object and negative if transferred from

the objectWork is a scalar quantity that has the same

units of Energy ( Joule )

What is work ?

What is the difference between work and doing work ? And what are theunits of work ?.

I applied the breaks to stop the carwhat work did friction do on my

car ?

Answer

Can we replace the forces bytheir resultant ?Then work is defined as:And work K.E theorem becomes

=10N

=12N

What is the work done by mg and N ?

Moving Down

Moving up

If it starts from rest and ends at restor if it moves with constant velocity then

Sample Problem

As the box is stationary at the the start and the end of the motion

Sample Problem

Alternative way