Exam 6: Force and Motion II

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.

The same heavy wooden block is dragged by a force along a rough steel plate, as shown below for two possible situations.The magnitude of the acceleration is the same for the two situations; do not assume that the magnitude of is the same.The magnitude of the frictional force in (ii), as compared with that in (i)is:

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:

Block A, with a mass of 10 kg, rests on a 35 $\degree$ 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 boy pulls a wooden box along a rough horizontal floor at constant speed by means of a force as shown.In the diagram f is the magnitude of the force of friction, N is the magnitude of the normal force, and F_g is the magnitude of the force of gravity.Which of the following must be true?

One end of a 1.0-m string is fixed; the other end is attached to a 2.0-kg stone.The stone swings in a vertical circle, passing the top point at 4.0 m/s.The tension force of the string at this point is about:

A horizontal force of 12 N pushes a 0.50-kg book against a vertical wall.The book is initially at rest.If $\mu$ _s = 0.60 and $\mu$ _k = 0.50, the acceleration of the book is:

A cube has a drag coefficient of 0.8.What would be the terminal velocity of a sugar cube 1 cm on a side in air (ρ = 1.2 kg/m³)? Take the density of sugar to be 1.6 x 10³ kg/m³.

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:

Block A, with a mass of 10 kg, rests on a 30 $\degree$ incline.The coefficient of kinetic friction is 0.20.The attached string is parallel to the incline and passes over a massless, frictionless pulley at the top.Block B, with a mass of 3.0 kg, is attached to the dangling end of the string.The acceleration of B is:

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:

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?

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:

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:

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:

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 = 0.50, the frictional force after a period of time is:

Uniform circular motion is the direct consequence of:

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:

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: