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Home Minds On Newton's Laws Mission NL5 Force Diagrams Help Help 4

Mission NL5 Force Diagrams

The Question

The diagrams below represent forces acting on an object. The size of the arrow represents the magnitude of the force. Which would be most consistent for the following scenario?
 

A 40.0 kg girl is suspended motionless from a bar that hangs from the ceiling.

Game Plan

Often times, success in physics demands that you have the proper approach - a good game plan. A good game plan for this question would be to:
 
  • First, identify if the forces are balanced or unbalanced; and if unbalanced, determine the direction of the unbalanced force (see Think About It section below). This will allow you to eliminate several choices from among the ten diagrams.
  • Second, use your understanding of the various force types to determine if there is a force in each direction - up, down, right, left. This requires that you have a good understanding of the different types of forces and when they are present and absent (use the link in the Hot Link section if necessary). This second step allows you to reduce the number of choices to one.

Think About It

If an object is at rest, then the individual forces acting upon it are balanced. Whichever force diagram you choose, make sure that it is a diagram representing a balance of forces. The up force arrow and the down force arrow should be the same size. And if there are horizontal force arrows, the right arrow should be the same size as the left arrow.

Hot Link