Chapter 5 Work and Energy. Section 5.1 Work. Work is done on an object only when a net force acts on the object to displace it in the direction of a component of the net force. Work = Force x displacement x cos Θ W= fd ( cosΘ ) Work is measured in Nm or Joules. Calculating Work.
When Force and Distance are in the same direction, cosΘ is 1 and W = Fd
A box is dragged across a floor by a 100N force directed 60o above the horizontal. How much work does the force do in pulling the object 8m?
Decide if work is done and if so, the sign of the work for each case:
a) A crane lifting a bucket of concrete
b) The force of gravity on the bucket being lifted
c) An athlete holds a weight up in a fixed position
d) An athlete lowers a weight slowly
e) A person pushes a book across the table.