Torques!

Two masses of mass 10.0 and 6.0 kg are hung from massless strings at the end of a light rod. The rod is virtually weightless. A pivot (fulcrum) is placed off center and the system is free to rotate. If the 6.0 kg mass is 4.0 m away from the pivot, how far away is the 10.0 kg mass if the system is not rotating?

• 0.42 m

• 2.4 m

• 4.8 m

• 4.2 m

Two masses of mass 10.0 and 6.0 kg are hung from massless strings at the end of a light rod. The rod is virtually weightless. A pivot (fulcrum) is placed off center and the system is free to rotate. If the string supporting the 10 kg mass is cut, find the net torque of the system.

• 24 Nm

• 60 Nm

• 240 Nm

• 480 Nm

1. Which of the following must be true for the system of two concentric massless pulleys and two masses shown in the picture for the system to be at equilibrium?

• m₁ = m₂

• m₁R₁ = m₂R₂

• m₁R₂ = m₂R₁

• m₁R₁² = m₂R₂²

Two wheels are fixed to each other and are free to rotate about a frictionless axis through their concentric centers. Four forces are exerted tangentially to the wheels. The magnitude of the net torque is:

• zero

• FR

• 2FR

• 4FR

Where should another 4 N force be applied to maximize the net torque on the object?

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• 
• 

Where should another 4 N force be applied to place the block in an equilibrium state?

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Tags

NGSS.HS-PS2-1

The easiest way to open a heavy door  is by applying the force

• Near the hinges
• In the middle of the door
• At the edge of the door far from the hinges
• At the top of the door

Tags

NGSS.HS-PS2-1

In the diagram above, two masses, one with mass m, the other with mass M = 2m are resting on a uniform plank of length L that pivots at its midpoint. If the mass m is at the far end of the plank, how far away from the pivot should the mass M be to balance the plank in a horizontal position shown?

• L/2
• L/3
• L/4
• L/6

Tags

NGSS.MS-PS2-4

A large disc with varying diameters is free to rotate about its axis located in the geometric center of the disc. According to the picture above, what will happen when the masses are released and the disc is free to rotate?

• The disc will spin clockwise, because the heavier mass exerts a large force on the disc, thus creating a large torque in the clockwise direction.

• The disc will spin counterclockwise, because the lighter mass applies a force to a longer lever-arm (r), thus creating more torque in the counterclockwise direction.

• The clock will not spin clockwise or counterclockwise because the torque produced by each hanging mass is equal, which puts the system in equilibrium and there will be no angular acceleration.

• It's impossible to tell which direction this wheel will rotate based on the diagram alone.

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?

• 0.666 Nm
•  133.3 N
• 66.7 N
• 13.3 Nm