STE - Center of Mass Revisited

Center of Mass Revisited

In a previous module we defined and learned how to calculate the center of mass using a standard equation for geometric shapes and calculus for irregular shapes. We can apply the same concept to objects in static equilibrium to determine the location of the pivot point. We can also use the center of mass to determine the change in position of two objects in a system if there is no external force applied. Please watch the following presentation to learn how to apply the center of mass to these two situations.

Center of Mass Revisited Practice

We will now practice solving problems using the concepts and relationships in the presentation.

Center of Mass Revisited Self-Assessment

  1. A 45.0 kg child stands at one end of an 80.0 kg raft that is 3.50 m long. The right side of the boat and boy are both initially 3.00 m from the shore.  The child sees a frog floating in place on the left side of the boat (further from shore) and decides he wants to capture it. He moves to the left side of the boat.
    1. Describe the motion of the boat and boy as he walks to the left side.
    2. How far is the boy from the shore when he gets to the left side of the boat?
    3. Assuming he can reach out 0.750 m and that the frog has not moved, can he pick up the frog?

SOLUTIONS Links to an external site.

  1. A 75.0 kg man stands in the middle of his ski boat that has a mass of 2540 kg and is 2.80 m wide. He carefully parks his boat up against the pier but forgets to tie up the boat. He takes a running start to jump onto the pier.
    1. How far from the edge of the pier is the boat by the time he gets to the edge? 
    2. If the edge of the boat is only 0.200 m above the pier and he leaves the boat with a horizontal velocity, how fast must he be going to land on the pier?

SOLUTIONS Links to an external site.

Center of Mass Revisited Practice Problems

Download Center of Mass Revisited Practice Problems Links to an external site. for more practice. 

Download solutions Links to an external site. to the practice problems. 

VIDEOS CREATED BY GAVS

IMAGES SOURCED FROM PUBLIC DOMAIN