Choose the best answer to each question and write the appropriate letter in the space provided.
1) Torque is defined
2) Suppose you try
loosening a nut with a wrench, and the nut doesn't give at all. You
increase your chance of success if you __________.
3) If a football
is kicked so the force on the ball is through its center of gravity,
the ball will __________.
4) The resistance
an object has to changes in its rotational state of motion is called
5) Which has more
rotational inertia, a bicycle wheel or a solid disk of the same mass
6) Which has more
rotational inertia, a girl running with her legs bent or the same girl
running with her legs straight?
7) Which objects
roll down an incline with the greatest acceleration?
8) Any solid cylinder
will roll down an incline with greater acceleration than any hollow
cylinder if the __________.
9) A person's rotational
inertia is least about __________.
10) When a gymnast
moves from an extended position to a tucked position, she __________.
11) Angular momentum
is defined as __________.
12) An object will
maintain its angular momentum unless acted on by an unbalanced force.
13) When an ice skater
pulls in his hands to turn faster __________.
14) If the planet
Jupiter underwent gravitational collapse, its rate of rotation about
its axis would __________.
15) Suppose a huge
rotating cloud of particles in space gravitates together to form a dense
ball. As the cloud shrinks in size it rotates __________.
16) Two people sit
on a balanced seesaw. When one person leans toward the center of the
seesaw, that person's end of the seesaw will __________.
17) To turn a stubborn
screw, it is best to use a screwdriver that has a __________.
18) Suppose a carnival
Ferris wheel has seats that are located halfway between the center and
the outside rim. Compared to the ordinary Ferris wheel, where the seats
are on the outside rim, your angular speed on this Ferris wheel would
19) Which rolls to
the bottom of a hill sooner, an empty car tire or the same tire mounted
on a rim?
20) A ring and a
disk roll down a hill together. Which reaches the bottom first?
21) A good explanation
of why a ball gains speed as it rolls down an incline involves the __________.
22) At the health
spa, Felix Flex finds that pulleys on the exercise machines are not
circular, but are "cams" -- sort of oval-shape. At different
orientations, the cams provide different __________.
23) A common thread
spool rests on a flat table. You gently pull in a horizontal direction
on a short piece of thread attached to (wrapped around) the spool. The
spool will roll toward you __________.
24) A common thread
spool rests on a flat table. You gently pull at an angle on a short
piece of thread attached to (wrapped around) the spool that causes the
spool to slide without rotating. With the thread at this angle, the
lever arm is __________.
25) A meter stick
is balanced at the 50-cm mark. You tie a 20-N weight at the 30-cm mark.
Where should a 30-N weight be placed so the meter stick will again be
26) A 2-kg ball is
whirled on the end of a string that is 3 m long. The ball's linear speed
is 2 m/s. What is its angular momentum?
27) A ring, a disk,
and a solid ball having equal masses roll down a hill at the same time.
Which reaches the bottom first?
Write True or False in the space provided.
28) The distance
between a turning axis and the point of contact of a perpendicular force
is called the fulcrum.
On a separate sheet of paper, answer the following questions.
38) Define torque.
When all the torques on an object are balanced, the object is in rotational
equilibrium. Apply this statement to two people sitting on either side
of a seesaw. Give an example.
Answer the following questions in the space provided. Show all work.
43) Suppose the torque
produced by a wrench on a stubborn nut is 20 N m. If the lever arm
is tripled with no change in force, what is the resulting torque?
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