Pearson ch08
The experimenter from the video rotates on his stool, this time holding his empty hands in his lap. You stand on a desk above him and drop a long, heavy bean bag straight down so that it lands across his lap, in his hands. What happens?
He spins slower.
How does the lever arm change if you decrease the angle of the force?
It decreases.
Is it easier for a circus performer to balance a long rod held vertically with people hanging off the other end, or the same long rod without the people at the other end, and why?
It is easier for the performer to balance a long rod held vertically with people at the other end because the rotational inertia is greater.
Is it easier to balance a long rod with a mass attached to it when the mass is closer to your hand or when the mass is farther away?
It is easier when the mass is farther from your hand
Why does the rotational inertia of the rod with the attached mass closer to your hand compare the way it does with the rotational inertial of the rod with the attached mass farther away?
Rotational inertia depends on whether the mass is farther or closer to the point of rotation. The farther the mass is, the higher the rotational inertia.
Which of the following statements correctly describes the system shown in the figure?
The angular acceleration of the pulley is nonzero.
Where is the center of gravity of the broom that Dr. Hewitt holds up?
at the balance point
Suppose we replace the mass in the video with one that is four times heavier. How far from the free end must we place the pivot to keep the meter stick in balance?
90 cm (10 cm from the weight)
How does the force needed to turn the wrench change if you increase the lever arm?
It decreases.
What happens when block B moves downward?
The cord's tension on the right side of the pulley is higher than on the left side.
How does the rotational inertia of the rod with the mass toward the bottom compare with the rotational inertia of the mass toward the top?
The rotational inertia of the rod with the mass closer to the top is greater than the rotational inertia of the rod with the mass closer to the bottom.
When Dr. Hewitt cuts the broom right through the center of gravity, how do the weights of the two sides of the broom compare?
The shorter side, where the bristles of the broom are, has a greater weight than the handle.
How does the lever arm change when you decrease the distance to the nut?
It decreases
How does the torque due to the weight of one side of the broom exerted around the balance point compare with the torque exerted by the weight of the other side of the broom around the balance point?
The torque due to the weight of the shorter side (the bristles of the broom) is equal in magnitude to the torque due to the weight of the longer side, and opposite in direction
