PH105                                                 Work-Energy Exercise

 

The work-energy theorem states that the net work done by all the forces acting on an object is equal to the change in kinetic energy of the object, W = DK = Kf – Ki.  In this exercise you will use Interactive Physics to study the work-energy principle for on a sliding block.

 

A.     No friction

  1. Place a 2-kg block on a frictionless surface and push the block with a 10-N force parallel with the surface.  Run the simulation and allow the block to move a few meters.  Using the distance the block has moved, calculate the work done and compare with the IP value of the block’s kinetic energy.

 

 

 

 

  1. Now rotate the 10-N force so that it pulls up at an angle of 30o from the surface.  Again, run the simulation, calculate the work done, and compare with the kinetic energy given by IP.

 

 

 

 

 

B.     With friction

 

1.      Set the coefficients of friction of the block and surface to 0.3.  Set the direction of the applied force so that it again pushes parallel with the surface.  Run the simulation so that the block slides a few meters.  Calculate the work done by the applied force and by friction.  Compare the total work done with the kinetic energy given by IP.

 

 

 

 

 

 

 

2.      Now rotate the 10-N force so that it pulls up at an angle of 30o.  Again, let the block slide a few meters, calculate the work done by the pull, by friction, and the total work, and compare with the IP value of the kinetic energy of the block.