Exam 4: Applying Newtons Laws

A locomotive is pulling three train cars along a level track exerting a force of 100,000 N.The car next to the locomotive has a mass of 80,000 kg,the next one,50,000 kg,and the last one,70,000 kg.You can neglect the friction on the cars being pulled. (a)What is the magnitude of the force that the 80,000-kg car exerts on the 50,000-kg car? (b)What is the magnitude of the force that the 50,000-kg car exerts on the 70,000-kg car?

A person is pushing on a box,exerting a force of magnitude P,as shown in the figure.Earth exerts force W on the box.The push is directed at an angle θ below the horizontal,and the box remains at rest.The box rests on a horizontal floor that has some friction with the box.The friction force exerted by the floor on the box is equal to

A vector in the xy-plane has an x component of -7.50 units.What must be the y component of this vector so that its magnitude is 10.0 units.(Note: There are two possible answers.)

As shown in the figure,a projectile is fired at time t = 0.00 s,from point 0 at the upper edge of a cliff,with initial velocity components of $v_{ 0 x} = 30 \mathrm {~m} / \mathrm { s }$ and $v_{ 0 y} = 300 \mathrm {~m} / \mathrm { s }$ The projectile rises and then falls into the sea at point P.The time of flight of the projectile is $75.0 \mathrm {~s} ,$ and air effects are negligible.At this location,g = 9.80 m/s².What is the horizontal distance D?

A 5.0-kg block and a 4.0-kg block are connected by a 0.6 kg rod,as shown in the figure.The links between the blocks and the rod are denoted by A and B.A vertical upward force of magnitude F of magnitude 150 N is exerted on the upper block.What magnitude force does each of the links A and B exert?

A wind farm generator uses a two-bladed propeller mounted on a pylon at a height of 20 m,as shown in the figure.The width of the pylon is very narrow,and the length of each propeller blade is 12 m.A tip of the propeller breaks off just when the propeller is vertical.The fragment flies off horizontally,falls,and strikes the ground at point P.Just before the fragment broke off,the propeller was turning uniformly,taking 1.2 s for each rotation.How far is point P from the base of the pylon if you neglect air?

A high-speed dart is shot from ground level with a speed of 150 m/s at an angle 30° above the horizontal.What is the vertical component of its velocity after 4.0 s if air effects can be neglected?

A very light wire is used to hang a series of 8.0-kg bricks.This wire will break if it exerts a force on an object greater than 450 N.The bricks are hung one below the other from a hook in the ceiling using this wire,as shown in the figure. (a)How many whole bricks can be hung without breaking the wire? (b)If you add one more brick to the number found in part (a),which string will break?

The eastward component of vector $\vec { A }$ is equal to the westward component of vector $\vec { B }$ and their northward components are equal.Which one of the following statements must be correct for these two vectors?

A 15-kg block is on a frictionless ramp that is inclined at 20° above the horizontal.It is connected by a very light string over an ideal pulley at the top edge of the ramp to a hanging 19-kg block,as shown in the figure.The string pulls on the 15-kg block parallel to the surface of the ramp.Find the magnitude of the acceleration of the 19-kg block after the system is gently released.

A marble moving 1.48 m/s rolls off the top edge of a 125-cm high table in a room where there is no appreciable air resistance and the free-fall acceleration is 9.80 m/s².Neglect effects of air. (a)How far from the base of the table will it strike the floor? (b)How long will it be in the air?

A slanted roof rises at 35° above the horizontal,and the straight-line distance from the top of the roof to the bottom edge is 4.5 m.The roof is covered with ice,so it offers no friction to objects sliding on it.A piece of ice at the top suddenly breaks loose and begins to slide down from rest. (a)How long will it take for the ice to reach the bottom edge of the roof? (b)How fast will the ice be traveling just as it reaches the bottom edge?

The figure shows a 100-kg block being released from rest from a height of 1.0 m.It then takes 0.53 s for it to reach the floor.What is the mass m of the block on the left? There is no friction or mass in the pulley,and the connecting rope is very light.

A 3.0-kg object and a 5.0-kg object hang vertically at the opposite ends of a rope that goes over an ideal pulley.If the objects are gently released from rest,how long does it take for the 3.0-kg objects to rise by 1.0 m?

At a location where g = 9.80 m/s²,a projectile returns to its original height after 4.08 seconds,during which time it travels 76.2 meters horizontally.If air can be neglected,what was the projectile's initial speed?

A 200-N sled of slides down a frictionless hillside that rises at 37° above the horizontal.What is the magnitude of the force that the hill exerts on the sled parallel to the surface of the hill?

You push horizontally on a 120-N box that is initially resting on a horizontal table.The coefficient of static friction between the box and the table is 0.75,and the coefficient of kinetic friction is 0.40.Find the friction force exerted on the box by the table if the push is equal to (a)84 N; (b)94 N.

A celebrating student throws a water balloon horizontally from a dormitory window that is 50 m above the ground.It hits the ground at a point 60 m from the building.Ignore air. (a)What will be the horizontal component of the velocity of the balloon just before it hits the ground? (b)What will be the magnitude of the vertical velocity of the balloon just before it hits the ground?

A load is being lifted vertically upwards by means of two cables attached to it.The first cable exerts a force of 600 N at an angle of 35.0° to the left of the vertical.The second cable exerts a force of 1300 N.At what angle to the right of the vertical is the second cable pulling?

A horizontal 52-N force must be exerted for a $50 - \mathrm { kg }$ box to slide across a flat surface at a constant velocity of 3.5 m/s.What is the coefficient of kinetic friction between the box and the floor?