Work and Conservation of Energy

definition of work done:

work done= force* distance moved in the direction of the force

An angled force pushes an object through some horizontal distance. We have seen that work done = force × distance moved in the direction of the force. Does the force do work on the object??

Yes, because a component of the force is in the direction of motion

Identify the correct S.I derived units of work

Joule (J)

The SI derived unit of work, the Joule, can be expressed in SI base units. Identify the correct expression

kgm²s^-2

A table is pushed across a polished floor. Select the correct way to explain work done in this situation.

We do work on the table by pushing it

definition of the Joule?

1 Joule is the work done when a force of 1 N moves its point of application 1 m in the direction of the force

An ice puck of mass 0.2 kg is sliding along an ice rink in a straight line. We can assume that friction and air resistance is zero and therefore the puck experiences zero force in the horizontal plane.

There is however a normal contact force from the ice acting upwards on the puck, as shown below.

Calculate the work done on the puck by the normal contact force.

Work done=Fcos(90)*x

=0J