Rotational Motion, Moment of Inertia and Torque

If the torque required to loosen a nut on the wheel of a car has a magnitude of 60.0 N• m, what minimum perpendicular force must be exerted by a mechanic at the end of a 45.0 cm wrench to loosen the nut?

• .666 Nm
•  133.3 N
• 66.7 N
• 13.3 Nm

Find the magnitude of the torque produced by a 5.0 N force applied to a door at a perpendicular distance of 65 cm from the hinge.

• 75 Nm
• 3.25 Nm
• 6.3 Nm
• 8.75 Nm

The figure shows scale drawings of four objects, each of the same mass and uniform thickness, with the mass distributed uniformly. Which one has the greatest moment of inertia when rotated at point P?

• A because all the mass is close to point P

• B because all the mass is far from point P

• C because it has a larger radius.

• D because it has less mass

A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii. If the three of them are released simultaneously at the top of an inclined plane and do not slip, which one will reach the bottom first?

• cylinder because it has uniformly distributed mass.

• pipe because it has a high MOI

• sphere because it has a small MOI

• They all reach the bottom at the same time.

The center of mass is in line with:

• the exact middle of an object

• the heaviest part of an object

• a point at which you can balance an object

• the idea that mass is evenly concentrated throughout

Stars originate as large bodies of slowly rotating gas. Because of gravity, these clumps of gas slowly decrease in size. What happens to the rotational speed of the star as it shrinks?

• It rotates faster.

• It rotates slower.

• It starts to accelerate in the forward direction.

• The rotation rate stays the same.

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

A seesaw with mass Z is perfectly balanced with a fulcrum in the center. If mass Z changes uniformly does the net torque change?

• Yes, because the Gravitational force increases with more mass, and torque is related to Force

• No, because the net torque is still zero despite increases in one of the individual components.

• No, because it is balanced that means net torque is zero, a uniform increase in weight keeps it balanced keeping net torque at zero

• Yes, any increase in weight will increase torque

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NGSS.MS-PS2-4

How do you get the maximum torque?

• longer lever arm and more force at an acute angle
• shorter lever arm with more force perpendicularly
• shorter lever arm and more force perpendicularly
• longer lever arm with more force perpendicularly

The force of gravity on an object.

• mass
• weight
• volume
• inertia

Tags

NGSS.HS-PS2-4

Torque is the product of a force exerted on an object x distance from the force to the axis of rotation.

• True 
• False