AP Physics 1 Question 174: Answer and Explanation

Test Information

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Question: 174

4.

An object hangs by a string from a car’s rearview mirror, as shown in the figure. The car is speeding up and moving to the right. Which of the following diagrams correctly represents the forces acting on the object?

  • A. T: Force of string on object
    W: Force of Earth on object
    Fo: Force of object on string
  • B. T: Force of string on object
    W: Force of Earth on object
    Fo: Force of object on string
  • C. T: Force of string on object
    W: Force of Earth on object
    Fo: Force of object on string
  • D. T: Force of string on object
    W: Force of Earth on object

Correct Answer: D

Explanation:

D-All of the diagrams have the object's weight correct. Any other force acting on the object must be provided by something in contact with that object. The only thing making contact with the object is the string, so add the force of the string on the object. That's it. The force of the object on the string doesn't go on this diagram, because this diagram only includes forces acting ON the object, not exerted by the object.