T3W3L1

A block of mass 3m can move without friction on a horizontal table. This block is attached to another block of mass m by a cord that passes over a frictionless pulley, as shown above. if the masses of the cord and the pulley are negligible, what is the magnitude of the acceleration of the descending block?

• g/4

• g/3

• 2g/3

• g

The magnitude of the normal force exerted on the block by the plane is

• greater than 20N

• greater than zero but less than 20N

• equal to 20N

• Zero

For which of the following motions of an object must the acceleration always be zero?

• Any motion in a straight line

• Simple harmonic motion

• Any motion at constant speed

• any single object in motion with constant momentum

A rope of negligible mass supports a block that weighs 30N, as shown above. The breaking strength of the rope is 50N. The largest acceleration that can be given to the block by pulling up on it with the rope without breaking the rope is most nearly

• 6.7m/s²

• 10m/s²

• 16.7m/s²

• 26.7m/s²

Multiple correct: the cart of mass 10kg shown moves without frictional loss on a level table. A 10N force pulls on the cart horizontally to the right. At the same time, a 30 N force at an angle of 60 degrees above the horizontal pulls on the cart to the left. Which of the following describes a manner in which this cart could be moving? Select two answers.

• moving left and speeding up

• moving left and slowing down

• moving right and speeding up

• moving right and slowing down

Two people are pulling on the ends of a rope. Each person pulls with a force of 100N. The tension in the rope is

• 0N

• 50N

• 100N

• 200N