Quiz #3.3 (A)

What is the magnitude of the torque produced by a 2.0 N force applied to a bottle opener at a perpendicular distance 8.0 cm from the bottle top?

• 0.40 N•m

• 0.16 N•m

• 16 N•m

• 40 N•m

If the torque needed to pry open a crate has a magnitude of 32.8 N•m, what is the minimum force that must be exerted at the end of a 0.900 m crowbar to open the crate?

• 0.602 N

• 0.488 N

• 57.3 N

• 36.4 N

A person lifts a 350 N crate using a pulley system. If the person exerts a 70 N force to lift the crate, what is the mechanical advantage of the pulley system?

• 1.25

• 5

• 4

• 0.25

A pulley system has an efficiency of 77.5 percent. How much work must you do to lift a desk weighing 1120 N to a height of 1.70 m?

• 3342 J

• 2457 J

• 1980 J

• 2260 J

The arm of a crane at a construction site is 15.0 m long, and it makes an angle of 20.0º with the horizontal. What is the magnitude of the maximum torque the crane can withstand if the maximum load the crane can handle is 450N?

• 2300 N•m

• 1200 N•m

• 6300 N•m

• 3700 N•m

Two students are balancing on a 10 m seesaw. The seesaw is designed so that each side of the seesaw is 5 m long. The student on the left weighs 60 kg and is standing three meters away from the center. The student on the right weighs 45 kg. The seesaw is parallel to the ground. Assume the board that makes the seesaw is massless. What distance from the center should the student on the

right be if they want the seesaw to stay parallel to the ground?

• 2.0 m

• 4.0 m

• 1.0 m

• 5.0 m

A construction worker is worried about applying too much torque to a bolt using his wrench. What could he do to reduce his torque on the bolt?

• increase the length of the wrench

• decrease the length of the wrench

• Increase the force on wrench

• decrease the friction between the bolt and wrench