Ch 8 Quiz practice
Center of mass
Toss a baseball bat into the air and it wobbles about its
None of the above
A 1-kg rock is suspended from the tip of a horizontal meterstick at the 0-cm mark so that the meterstick barely balances like a seesaw when its fulcrum is at the 12.5-cm mark. From this information, the mass of the meterstick is
An unbalanced torque
A ball gains speed while rolling down a hill due mainly to
The boy
A boy plays solitary seesaw by placing the seesaw's fulcrum one-eighth the distance from where he sits at one end. Which weighs more?
Sphere
A ring, a disk, and a solid sphere begin rolling down a hill together. Which reaches the bottom first?
More than the weight of the seesaw
A solitary boy cannot balance on a seesaw with its fulcrum at its midpoint. If the fulcrum is moved to one-quarter the distance from the boy, balance is achieved when the weight of the boy is
4 m
A swimming area in a rotating space habitat is located in a region of 1/4 g. If a diver can jump 1 m high in a 1-g region, how high can the same diver jump in the swimming area?
Droops
A tightrope walker more easily balances on a tight wire if her pole
Rotation
A torque acting on an object tends to produce
At the top, away from your hand
A vertically-held sledge hammer is easier to balance when the heavier end is
Basketball
Which of these has its center of mass where no mass exists?
Rotating
Centrifugal forces are an apparent reality to observers in a reference frame that is
Centripetal force has no component in the direction of motion
Centripetal force does no work on a circularly-moving object because
Two times greater
Consider two flywheels of the same size and shape, but one with twice the mass. Rotational inertia of the more massive one is
Torque
If Alex wishes to rotate his skateboard, then he must apply a
At the center of the Earth
If Earth had a pair of identical moons on opposite sides of the same circular orbit, the center of gravity of the double-moon-Earth system would be
Double
If a turntable's rotational speed is doubled, then the linear speed of a pet hamster sitting on the edge of the record will
Bristles part
If you balance a broom horizontally on one finger, the center of gravity of the broom will be above your finger, closer to the bristles end than the handle end. If you saw the broom in two pieces at that point and weigh the two parts on a scale, you'll find that the heavier part is the
Two
If you place a pipe over the end of a wrench when trying to rotate a stubborn bolt, effectively making the wrench handle twice as long, you'll multiply the torque by
1/3 the distance from the fulcrum
On a balanced seesaw, a boy three times as heavy as his partner sits
Bristles end
Stand a broom upright on the end of its pole and let it topple to the floor. Repeat, but with the bristles end on the floor. The faster fall will be the broom standing on its
Longer
Stand a meterstick on its end and let it rotate to the floor. If you attach a heavy glob of clay to its upper end and repeat, the time to fall will be
circular path
The bob of a conical pendulum swings in a
Changes as a person bends over
The center of mass of a human body is located at a point that
Slows
The chef at the infamous Fattening Tower of Pizza tosses a spinning disk of uncooked pizza dough into the air. The disk becomes wider during its flight, while its rotational speed
Above a place of support
The famous Leaning Tower of Pisa doesn't topple over because its center of gravity is
The radial component of the normal force.
The force responsible for a car moving steadily along a no-friction icy banked curve is due to
g
The gravitational field simulated by rotation in a space habitat that is best suited for humans is
Spin of the Earth
The main reason a person weighs less at the equator than at the poles involves the
Directed toward the center of the curve
The net force exerted on a car traveling in a circular path at constant speed is
Travel at different linear speeds for the same rotational speed, in effect vary their diameters. Both of these.
The tapered shape of the wheel rims that ride on railroad tracks allows opposite wheels to
Through its center of gravity
To kick a football so it won't topple end over end, kick it so the force of impact extends
Rise
Two people are balanced on a seesaw. If one person leans inward toward the center of the seesaw, that person's end of the seesaw tends to
Cover different distances per revolution
When a train makes a curve, a tapered wheel rim is able to
Increases
When a twirling ice skater brings her arms inward, her rotational speed
Directly above the point between wheels below
When riding at constant velocity on a Segway electric vehicle, your center of mass is
The filled jar
Which jar will roll down an incline in the shortest time, an empty one or one filled with peanut butter?
Mouse
Which of these animals has a quicker stride?
The same.
You can safely stand on the overhanging end of a heavy plank that rests on a table. How much overhang depends on your mass and the plank's mass. If you can stand on the end of a plank that overhangs the edge of the supporting table 1/4 its total length, how massive is the plank compared to your mass?