Exam 10: Motion in a Plane

In the figure,a constant external force P = 160 N is applied to a 20.0-kg box,which is on a rough horizontal surface.While the force pushes the box a distance of 8.00 m,the speed changes from 0.500 m/s to 2.60 m/s.The work done by friction during this process is closest to

A child throws a ball with an initial speed of 8.00 m/s at an angle of 40.0° above the horizontal.The ball leaves her hand 1.00 m above the ground and experience negligible air resistance. (a) How far from where the child is standing does the ball hit the ground? (b) How long is the ball in flight before it hits the ground?

Alice and Tom dive from an overhang into the lake below.Tom simply drops straight down from the edge,but Alice takes a running start and jumps with an initial horizontal velocity of 25 m/s.Neither person experiences any significant air resistance.Compare the time it takes each of them to reach the lake below.

A brick is resting on a rough incline as shown in the figure.The friction force acting on the brick,along the incline,is

The components of vector are B_x = -3.5 and B_y = -9.7,and the components of vector Are C_x = -6 and C_y = +8.1.What is the angle (less than 180 degrees)between vectors And ?

What is the maximum distance we can shoot a dart,from ground level,provided our toy dart gun gives a maximum initial velocity of 2.78 m/s and air resistance is negligible?

An apple falls from an apple tree growing on a 20° slope.The apple hits the ground with an impact velocity of 16.2 m/s straight downward.What is the component of the apple's impact velocity parallel to the surface of the slope?

A system of blocks and a frictionless pulley is shown in the figure.Block A has a mass of 2.0 kg and is on a rough horizontal surface for which μ_s = 0.40 between the surface and block A.The rope pulls horizontally on block A.Block C has a mass of 1.0 kg.An external force P = 23.0 N,applied vertically to block A,maintains the system at rest as shown in the figure.What is the friction force on block A?

Two boys searching for buried treasure are standing underneath the same tree.One boy walks 18 m east and then 18 m north. The other boy walks 16 m west and then 11 m north. Find the scalar product of their net displacements from the tree.

In a shuffleboard game,the puck slides a total of 12 m before coming to rest.If the coefficient of kinetic friction between the puck and the horizontal board is 0.28,what was the initial speed of the puck?

A 6.0 kg box slides down an inclined plane that makes an angle of 39° with the horizontal.If the coefficient of kinetic friction is 0.19,at what rate does the box accelerate down the slope?

A 200 g hockey puck is launched up a metal ramp that is inclined at a 30° angle.The coefficients of static and kinetic friction between the hockey puck and the metal ramp are μ_s = 0.40 and μ_k = 0.30,respectively.The puck's initial speed is 4.9 m/s.What speed does it have when it slides back down to its starting point?

In the figure,a block of mass m is moving along the horizontal frictionless surface with a speed of 5.70 m/s.If the slope is 11.0° and the coefficient of kinetic friction between the block and the incline is 0.260,how far does the block travel up the incline?

You walk 55 m to the north,then turn 60° to your right and walk another 45 m.How far are you from where you originally started?

An object of mass 4.0 kg starts at rest from the top of a rough inclined plane of height 10 m as shown in the figure.If the speed of the object at the bottom of the inclined plane is 10 m/s,how much work does friction do on this object as it slides down the incline?

A hiker throws a stone from the upper edge of a vertical cliff.The stone's initial velocity is 25.0 m/s directed at 40.0° with the face of the cliff,as shown in the figure.The stone hits the ground 3.75 s after being thrown and feels no appreciable air resistance as it falls. (a) What is the height of the cliff? (b) How far from the foot of the cliff does the stone land? (c) How fast is the stone moving just before it hits the ground?

In the figure,a 700-kg crate is on a rough surface inclined at 30°.A constant external force P = 5600 N is applied horizontally to the crate.As the force pushes the crate a distance of 3.00 m up the incline,the speed changes from 1.40 m/s to 2.50 m/s.How much work does gravity do on the crate during this process?

A factory robot drops a 10 kg computer onto a conveyor belt running at 3.1 m/s.The materials are such that μ_s = 0.50 and μ_k = 0.30 between the belt and the computer.How far is the computer dragged before it is riding smoothly on the belt?

In the figure,two wooden blocks each of 0.30 kg mass are connected by a string that passes over a very light frictionless pulley. One block slides on a horizontal table,while the other hangs suspended by the string,as shown in the figure.At time t = 0,the suspended block is 0.80 m over the floor,and the blocks are released from rest.After 2.5 s,the suspended block reaches the floor.What is the coefficient of kinetic friction between the table and the sliding block?

A 900-kg car traveling east at 15.0 m/s collides with a 750-kg car traveling north at 20.0 m/s.The cars stick together.Assume that any other unbalanced forces are negligible. (a)What is the speed of the wreckage just after the collision? (b)In what direction does the wreckage move just after the collision?