A2L Item 032

• Description: Identify the graph of the vertical component of force on a ball rolling on a horizontal, then sloped surface.
• Goal: Hone the vector nature of force and how the net force can be determined from the 2nd law.
• Source: UMPERG
• Keywords: Dynamics, Forces, Mechanics

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The question for students:

A soccer ball rolls across the road and down a hill as shown below.

Which of the following sketches of Fy vs. t represents the net vertical force on the ball as a function of time?

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Commentary for teachers:

Answer

(4); on the horizontal partion there is no net force, and therefore no F_y. On the slope the net force in the y direction is due to gravity and a component of the normal force. Alternatively, since the ball accelerates along the slope, the net force must be parallel to the slope and have a component in the vertical direction.

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