Exam 5: More Applications of Newtons Laws

In a game of shuffleboard (played on a horizontal surface),a puck is given an initial speed of 6.0 m/s.It slides a distance of 9.0 m before coming to rest.What is the coefficient of kinetic friction between the puck and the surface?

A 4.0-kg mass on the end of a string rotates in a circular motion on a horizontal frictionless table.The mass has a constant speed of 2.0 m/s and the radius of the circle is 0.80 m.What is the magnitude of the resultant force acting on the mass?

A sample of blood is placed into a centrifuge of radius 15.0 cm.The mass of a red corpuscle is 3.0 *10 ^{- 16} kg,and the centripetal force required to make it settle out of the plasma is 4.0 *10 ^{- 11} N.At how many revolutions per second should the centrifuge be operated?

A 0.50 kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m).When the mass is at the highest point of the circle the speed of the mass is 8.0 m/s.What is the magnitude of the force of the string on the mass at this position?

A rock attached to a string swings in a vertical circle.Which free body diagram could correctly describe the force(s)on the rock when it is at the highest point?

A 0.20-kg object attached to the end of a string swings in a vertical circle (radius = 80 cm).At the top of the circle the speed of the object is 4.5 m/s.What is the magnitude of the tension in the string at this position?

A box is dropped onto a conveyor belt moving at 2 m/s.If the coefficient of friction between the box and the belt is 0.3,how long before the box moves without slipping?

If a 20-kg object dropped in air has a terminal speed of 60 m/s,what was its acceleration at 30 m/s?

When a car goes around a circular curve on a level road without slipping,

The first of two identical boxes of mass m is sitting on level ground.The second box is sitting on a ramp that makes an angle with the ground.When a force of magnitude F is applied to each box in a direction parallel to the surface it is on,upwards on the box on the ramp,neither box moves.Which statement comparing the friction force on the box on the level,f_L,to the friction force on the box on the ramp,f_R,is correct?

In the figure shown,the coefficient of kinetic friction between the block and the incline is 0.29.What is the magnitude of the acceleration of the suspended block as it falls? Disregard any pulley mass or friction in the pulley.

The equation below is the solution to a problem. $\frac { ( 2.00 \mathrm {~kg} ) \left( 8.00 \frac { \mathrm { m } } { \mathrm { s } } \right) ^ { 2 } } { 5.00 \mathrm {~m} } = 45.2 \mathrm {~N} - ( 2.00 \mathrm {~kg} ) \left( 9.80 \frac { \mathrm { m } } { \mathrm { s } ^ { 2 } } \right) \left( \cos 0 ^ { \circ } \right)$ . The best physical representation of this equation is

The coefficient of kinetic friction between the surface and the larger block is 0.25,and the coefficient of kinetic friction between the surface and the smaller block is 0.40.If F = 22N and M = 1.0 kg in the figure,what is the magnitude of the acceleration of either block?

In the figure,the coefficient of kinetic friction between the surface and the larger block is 0.20,and the coefficient of kinetic friction between the surface and the smaller block is 0.30.If F = 14 N and M = 1.0 kg,what is the magnitude of the acceleration of either block?

The total force needed to drag a box at constant speed across a surface with coefficient of kinetic friction $\theta$ _k is least when the force is applied at an angle $\theta$ such that

A 0.50-kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m).When the mass is at the lowest point on the circle,the speed of the mass is 12 m/s.What is the magnitude of the force of the string on the mass at this position?

A skydiver of 75 kg mass has a terminal velocity of 60 m/s.At what speed is the resistive force on the skydiver half that when at terminal speed?

A 1.8-kg block is projected up a rough 10 $\degree$ inclined plane.As the block slides up the incline,its acceleration is 3.8 m/s² down the incline.What is the magnitude of the force of friction acting on the block?

An amusement ride consists of a car moving in a vertical circle on the end of a rigid boom.The radius of the circle is 10 m.The combined weight of the car and riders is 5.0 kN.At the top of the circle the car has a speed of 5.0 m/s which is not changing at that instant.What is the force of the boom on the car at the top of the circle?

A roller-coaster car has a mass of 500 kg when fully loaded with passengers.The car passes over a hill of radius 15 m,as shown.At the top of the hill,the car has a speed of 8.0 m/s.What is the force of the track on the car at the top of the hill?