Exam 6: Force and Motion

A 400-N block is dragged along a horizontal surface by an applied force as shown.The coefficient of kinetic friction is u_k = 0.4 and the block moves at constant velocity.The magnitude of is:

A giant wheel, having a diameter of 40 m, is fitted with a cage and platform on which a man of mass m stands.The wheel is rotated in a vertical plane at such a speed that the force exerted by the man on the platform is equal to his weight when the cage is at X, as shown.The net force on the man at point X is:

An automobile moves on a level horizontal road in a circle of radius 30 m.The coefficient of friction between tires and road is 0.50.The maximum speed with which this car can round this curve is:

A horizontal force of 12 N pushes a 0.50-kg book against a vertical wall.The book is initially at rest.If the coefficients of friction are = 0.60 and = 0.50 which of the following is true?

If a certain car, going with speed v₁, rounds a level curve with a radius R₁, it is just on the verge of skidding.If its speed is now doubled, the radius of the tightest curve on the same road that it can round without skidding is:

A 40-N crate rests on a rough horizontal floor.A 12-N horizontal force is then applied to it.If the coefficients of friction are = 0.5 and = 0.4, the magnitude of the frictional force on the crate is:

A force (larger than the largest possible force of static friction)is applied to the left to an object moving to the right on a horizontal surface.Then:

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, attached to the dangling end, for which A remains at rest is:

Block A, with a mass of 50 kg, rests on a horizontal table top.The coefficient of static friction is 0.40.A horizontal string is attached to A and passes over a massless, frictionless pulley as shown.The smallest mass m_B of block B, attached to the dangling end, that will start A moving when it is attached to the other end of the string is:

A person riding a Ferris wheel is strapped into her seat by a seat belt.The wheel is spun so that the centripetal acceleration is g.Select the correct combination of forces that act on her when she is at the top.Here, F_g = force of gravity, down; F_b = seat belt force, down; and F_s = seat force, up.

A horizontal force of 12 N pushes a 0.50-kg book against a vertical wall.The book is initially at rest.If = 0.60 and = 0.50, the acceleration of the book 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 = 0.60 and = 0.50, the frictional force after a period of time is:

In uniform circular motion,

A block is placed on a rough wooden plane.It is found that when the plane is tilted 30F° to the horizontal, the block will slide down at constant speed.The coefficient of kinetic friction of the block with the plane is: