Reading Quiz 16 Key

# Reading Quiz 16 Key

## Due 3:30 pm, Thursday, October 22nd

Physics 105, Fall Term, 2009

Did you complete the reading assignment?

Yes
No

## KEY CONCEPTS:

1) The direction of torque is either clockwise or counterclockwise

2) Rotational equilibrium occurs when torques are balanced

Go to: http://www.ngsir.netfirms.com/englishhtm/Torque.htm.  The controls can be a little strange at first. Look at the quick explanations below the applet for how to use the controls. The most helpful view is the view that shows the numbers rather than the pictures. It is often easier to to adjust the position of the pivot point that it is to change the position of the mass or spring scale. Click the box labeled 'Spring balance vertical, beam horizontal'; this will force the beam to be in equilibrium in a horizontal position and will change the force on the spring scale to make it physically possible to be in rotational equilibrium.

Move the pivot point back and forth between the mass and spring scale while observing the changes in the spring scale. Is the force applied by the spring scale always the same as the force of gravity acting on the mass?

Yes
No

What happens to the force applied by the spring scale when the pivot point is moved closer to the mass?

Increases force
Decreases force
Force stays the same

What happens to the force applied by the spring scale when the force of gravity acting on the mass is increased?

Increases force
Decreases force
Force stays the same

Two weights of equal mass are placed on opposite sides of a pivot point on a beam. What must be true about the distances of the masses from the pivot point for the beam to be in rotational equilibrium?

To keep the beam in rotational equilibrium, would the direction of the torque of the spring scale need to change if the spring scale was put on the same side of the pivot point as the mass? Why or why not?

To keep the beam in rotational equilibrium, would the direction of the force of the spring scale need to change if the spring scale was put on the same side of the pivot point as the mass? Why or why not?

FEEDBACK

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Was there anything that you didn't understand in the reading assignment?  What was confusing to you?