Exam 5: Applications of Newtons Laws

A boy is standing at the stern (back) of a boat that is 8.0 m long. There is no friction between the boat and the water. The boy has a mass of 63 kg and the boat has a mass of 780 kg. The bow (front) of the boat is touching a dock and the fore-and-aft axis of the boat is perpendicular to the dock. The boy walks from the stern of the boat to the bow. When he reaches the bow, his distance from the dock is

As a sky diver falls through the air, her terminal speed

A box (m = 20 kg) is sitting on a horizontal surface. It is connected to a massless hook by a light string passing over a massless pulley wheel. The coefficients of friction between the box and the surface are 0.50 (static) and 0.30 (kinetic). On top of m is a second box M of mass 20 kg. The coefficients of friction between the boxes m and M are 0.80 (static) and 0.60 (kinetic). How much weight needs to be added to the hook until the box just begins to move.

The blocks shown in the figures have equal masses and are made of the same material. The velocity is the same in each figure. The total frictional force exerted by the surface on the blocks is

The mass of the rectangle in the figure is M, the mass of the ring is M, and the mass of the circle is 3M. The center of mass of the system with respect to the origin O is located at point

A ball of mass m is attached to a thin string and whirled in a vertical circle or radius r. The tension in the string at point e where the ball is moving with speed v is

A block slides down a frictionless incline. The path at the bottom of the incline is an arc of a circle. The direction of the net force on the block at the bottom of the arc (point P) is along (use the compass rose)

If a jet plane doubles the speed, the drag force on the jet plane

A car going around a curve of radius R at a speed V experiences a centripetal acceleration a_c. What is its acceleration if it goes around a curve of radius 3R at a speed of 2V?

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. Assume that air resistance is negligible. The free-body diagram that best represents the acceleration of the ball is

A block of mass m is pulled in the direction shown in the figure across a rough surface with a constant acceleration . The magnitude of the frictional force is

A mass m is placed on a rough incline at an angle $\theta$ to the horizon. A force F is applied up the incline, to prevent the mass from sliding down the incline, and it is just enough to prevent the mass from sliding down the incline. Using the compass rose, the direction of the frictional force is along

A mass m is placed on a rough incline at an angle $\theta$ to the horizon. A force F is applied up the incline so that the mass slides up the incline. Using the compass rose, the direction of the frictional force is along

A 1.0-kg mass is acted on by a net force of 4.0 N and a 3.0-kg mass is acted on by a net force of 3.0 N, in the directions shown. The acceleration of the center of mass of this system is approximately

In the equation F = bv, F is the force on an object that is moving in a viscous medium, b is a constant, and v is the speed of the falling object. The SI units of the constant b are

The figure shows a top view of a ball on the end of a string traveling counterclockwise in a circular path. Assume that air resistance is negligible. The free-body diagram that best represents the net force acting on the ball is

A worker pulls horizontally on a rope that is attached to a 10-kg crate resting on a rough floor. The coefficients of static and kinetic friction are 0.5 and 0.3, respectively. The worker pulls with a force of 40 N. The frictional force exerted by the surface is

A heavy truck and a light car are traveling at the same speed on the same roadway. If the coefficients of static friction between their tires and the road are the same, which vehicle will be able to stop in the shortest distance? Assume both have the same braking force.

A block is placed on a plane whose angle of inclination is 30º. The coefficients of static and kinetic friction for the block on the inclined plane are both 0.2. The block

A barbell is 1.5 m long. Three weights, each of mass 20 kg, are hung on the left and two weights of the same mass, on the right. The width of each weight is 4 cm and each group of weights is placed 4 cm from the ends. Where is the center of mass of the barbell as measured from the mid-point, M, of the bar? The bar is of uniform mass and has mass 5 kg, and the retaining collars are of negligible mass. Take to the right as positive.