Exam 6: Force and Motion

A 0.2-kg stone is attached to a string and swung in a circle of radius 0.6 m on a horizontal and frictionless surface.If the stone makes 150 revolutions per minute, the tension force of the string on the stone is:

Block A, with mass m_A, is initially at rest on a horizontal floor.Block B, with mass m_B, is initially at rest on the horizontal top surface of A.The coefficient of static friction between the two blocks is $\mu$ $\mu$ _s.Block A is pulled with a horizontal force.It begins to slide out from under B if the force is greater than:

A 5.0-kg crate is on an incline that makes an angle of 30°with the horizontal.If the coefficient of static friction is 0.50, the minimum force that can be applied parallel to the plane to hold the crate at rest is:

A crate is sliding down an incline that is 35°above the horizontal.If the coefficient of kinetic friction is 0.40, the acceleration of the crate is:

A baseball has a terminal speed of 42 m/s in air (ρ = 1.2 kg/m³).What would be its terminal speed in water (ρ = 1.0 x 10³ kg/m³)?

A 1000-kg airplane moves in straight flight at constant speed.The force of air friction is 1800 N.The net force on the plane is:

A coin is placed on a horizontal phonograph turntable.Let N be the normal force exerted by the turntable on the coin, f be the frictional force exerted by the turntable on the coin, and f_{s, max} be the maximum force of the static friction.The speed of the turntable is increased in small steps.If the coin does not slide, then

Which of the following five graphs is correct for a particle moving in a circle of radius r at a constant speed of 10 m/s?

The driver of a 1000-kg car tries to turn through a circle of radius 100 m on an unbanked curve at a speed of 10 m/s.The actual frictional force between the tires and a slippery road has a magnitude of 900 N.The car:

An object moving in a circle at constant speed:

Circular freeway entrance and exit ramps are commonly banked to handle a car moving at 13 m/s.To design a similar ramp for 26 m/s one should:

An object of mass m and another object of mass 2m are each forced to move along a circle of radius 1.0 m at a constant speed of 1.0 m/s.The magnitudes of their accelerations are:

A forward horizontal force of 12 N is used to pull a 240-N crate at constant velocity across a horizontal floor.The coefficient of friction is:

A bureau rests on a rough horizontal surface ( = 0.50, = 0.40).A constant horizontal force, just sufficient to start the bureau in motion, is then applied.The acceleration of the bureau is:

The speed of a 4.0-N hockey puck, sliding across a level ice surface, decreases at the rate of 0.61 m/s².The coefficient of kinetic friction between the puck and ice 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:

At what angle should the roadway on a curve with a 50m radius be banked to allow cars to negotiate the curve at 12 m/s even if the roadway is icy (and the frictional force is zero)?

Block A, with a mass of 10 kg, rests on a 35°incline.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, of block B, attached to the dangling end, for which A begins to slide down the incline, is:

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 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.