Exam 3: Forces and Motion in One Dimension

Two blocks, joined by a string, have masses of 6.0 and 9.0 kg. They rest on a frictionless, horizontal surface. A second string, attached only to the 6.0-kg block, has horizontal force = 45 N applied to it. Both blocks accelerate. Find the tension in the string between the blocks.

A ball is thrown vertically upwards at 29.4 m/s. For its complete trip (up and back down to the starting position), its average speed is:

Assume everyone in the United States consumes one soft drink in an aluminum can every two days. If there are 300 million Americans, how many tons of aluminum need to be recycled each year if each can weighs 1/16 pound, and one ton = 2000 pounds?

Three identical 3.0-kg cubes are placed on a horizontal surface in contact with one another. The cubes are lined up from left to right and an 18-N force is applied to the left side of the left cube causing all three cubes to accelerate to the right. If the cubes are each subject to a frictional force of 3.0 N, what is the magnitude of the force exerted on the middle cube by the left cube in this case?

A cheetah can run at approximately 100 km/hr and a gazelle at 80.0 km/hr. If both animals are running at full speed, with the gazelle 60.0 m ahead, how long before the cheetah catches its prey?

A cue ball of weight W is falling with acceleration g/2 downward and speed v. What would be the terminal velocity of this ball as it continues to fall?

A steel sphere of mass M has a large spherical cavity inside. A second solid steel sphere has mass 4M, but has the same outer radius as the first sphere. If the terminal velocity of the first sphere is v, what would be the terminal velocity of the second sphere?

An automobile of mass 2000 kg moving at 20 m/s is braked suddenly with a constant braking force of 10,000 N. How far does the car travel before stopping?

The maximum possible value for the coefficient of static friction is:

Two blocks of masses 20 kg and 8.0 kg are connected together by a light string and rest on a frictionless, level surface. Attached to the 8.0-kg mass is a second light string, which a person uses to pull both blocks horizontally. If the two-block system accelerates at 1.0 m/s², what is the tension in the second string attached to the 8.0-kg mass?

A rock is rolled in the sand. It starts at 5.0 m/s, moves in a straight line for a distance of 6.0 m, and then stops. What is the magnitude of the average acceleration?

When a drag strip vehicle reaches a velocity of 60 m/s, it begins a negative acceleration by releasing a drag chute and applying its brakes. While reducing its velocity back to zero, its acceleration along a straight line path is a constant -6.0 m/s². What displacement does it undergo during this deceleration period?

Three identical 6.0-kg cubes are placed on a horizontal frictionless surface in contact with one another. The cubes are lined up from left to right and a force is applied to the left side of the left cube causing all three cubes to accelerate to the right at 3.0 m/s². What is the magnitude of the force exerted on the middle cube by the left cube in this case?

A rock is thrown straight up with an initial velocity of 24.5 m/s. What time interval elapses between the rock's being thrown and its return to the original launch point? (Acceleration due to gravity is 9.80 m/s².)

An automobile driver puts on the brakes and decelerates from 30.0 m/s to zero in 12.0 s. What distance does the car travel?

A barefoot field-goal kicker imparts a speed of 30 m/s to a football at rest. If the football has a mass of 0.50 kg and time of contact with the football is 0.020 s, what is the force exerted on the foot?

Two objects of different mass are released simultaneously from the top of a 20-m tower and fall to the ground. If air resistance is negligible, which statement best applies?