Exam 6: Force and Motion II

A block is first placed on its long side and then on its short side on the same inclined plane. The block slides down the plane on its short side but remains at rest on its long side. A possible explanation is:

A professor holds an eraser against a vertical chalkboard by pushing horizontally on it. He pushes with a force that is much greater than is required to hold the eraser. The force of friction exerted by the board on the eraser increases if he:

The system shown remains at rest. The force of friction on the upper block is:

A block of mass m is pulled at constant velocity along a rough horizonatl floor by and applied force as shown. The magnitude of frictional force is:

A ball is thrown upward into the air with a speed that is greater than terminal speed. It lands at the place where it was thrown. During its flight the force of air resistance is the greatest:

A 50-N force is applied to a crate on a horizontal rough floor, causing it to move horizontally. If the coefficient of kinetic friction is 0.50, in what direction should the force be applied to obtain the greatest acceleration?

The magnitude of the force required to cause an 0.04-kg object to move at 0.6 m/s in a circle of radius 1.0 m is:

A crate rests on a horizontal surface and a woman pulls on it with a 10-N force. No matter what the orientation of the force, the crate does not move. Rank the situations shown below according to the magnitude of the frictional force of the surface on the crate, least to greatest.

A block is suspended by a rope from the ceiling of a car.. When the car rounds a 45-m radius horizontal curve at 22 m/s (about 50 mph), what angle does the rod make with the vertical?

Block A, with a mass of 10 kg, rests on a 35incline. The coefficient of static friction is 0.40. An attached string is parallel to the incline and passes over a massless, frictionless pulley at the top. The largest mass m_B, attached to the dangling end, for which A remains at rest is:

A car is traveling at 15 m/s on a horizontal road. The brakes are applied and the car skids to a stop in 4.0 s. The coefficient of kinetic friction between the tires and road is:

A crate resting on a rough horizontal floor is to be moved horizontally. The coefficient of static friction is 0.40. To start the crate moving with the weakest possible applied force, in what direction should the force be applied?

A horizontal force of 12 N pushes a 0.5-kg bookk against a vertical wall. The book is initially at rest. If the coefficients of friction are $\mu$ _s = 0.6 and $\mu$ _k = 0.8 which of the following is true?

A box rests on a rough board 10 meters long. When one end of the board is slowly raised to a height of 6 meters above the other end, the box begins to slide. The coefficient of static friction is:

A horizontal force of 5.0 N pushes a 0.50-kg block against a vertical wall. The block is initially at rest. If $\mu$ _s = 0.60 and $\mu$ _k = 0.80, the acceleration of the block in m/s² is:

A horizontal force of 5.0 N pushes a 0.50-kg block against a vertical wall. The block is initially at rest. If $\mu$ _s = 0.6 and $\mu$ _k = 0.80, the frictional force is:

A giant wheel, 40 m in diameter, is fitted with a cage and platform on which a man can stand. The wheel rotates at such a speed that when the cage is at X (as shown) the force exerted by the man on the platform is equal to his weight. The speed of the man is:

When the brakes of an automobile are applied, the road exerts the greatest retarding force:

A block of mass m is pulled along a rough horizontal floor by an applied force as shown. The vertical component of the force exerted on the block by the floor is:

Why do raindrops fall with constant speed during the later stages of their descent?