Exam 6: Work and Kinetic Energy

Block A (0.40 kg)and block B (0.30 kg)are on a frictionless table (see figure).Spring 1 connects block A to a frictionless peg at 0 and spring 2 connects block A and block B.When the blocks are in uniform circular motion about 0,the springs have lengths of and ,as shown.The springs are ideal and massless,and the linear speed of block B is 2.0 m/s.If the distance that spring 2 stretches is 0.060 m,the spring constant of spring 2 is closest to

It requires 49 J of work to stretch an ideal very light spring from a length of 1.4 m to a length of 2.9 m.What is the value of the spring constant of this spring?

How long will it take a 7.08 hp motor to lift a 250 kg beam directly upward at constant velocity from the ground to a height of 45.0 m? Assume frictional forces are negligible.

In the figure,two boxes,each of mass 24 kg,are at rest and connected as shown.The coefficient of kinetic friction between the inclined surface and the box is 0.31.Find the speed of the boxes just after they have moved 1.6 m.

In the figure,two identical ideal massless springs have unstretched lengths of and spring constants of 700 N/m.The springs are attached to a small cube and stretched to a length L of 0.30 m as in Figure A.An external force P pulls the cube a distance to the right and holds it there.(See Figure B.)The external force P,that holds the cube in place in Figure B,is closest to

A 1000.0 kg car is moving at If a truck has 18 times the kinetic energy of the car,how fast is the truck moving?

A 1000 kg car experiences a net force of 9500 N while decelerating from 30.0 m/s to .How far does it travel while slowing down?

An object attached to an ideal massless spring is pulled across a frictionless surface.If the spring constant is 45 N/m and the spring is stretched by 0.88 m when the object is accelerating at what is the mass of the object?

A force = 12 N - 10 N acts on an object.How much work does this force do as the object moves from the origin to the point

Three forces,F₁ = 20.0 N,F₂ = 40.0 N,and act on an object with a mass of which can move along a frictionless inclined plane as shown in the figure.The questions refer to the instant when the object has moved through a distance of 0.600 m along the surface of the inclined plane in the upward direction.Calculate the amount of work done by (a)F_1. (b)F_2. (c)F₃.

Two objects,one of mass m and the other of mass 2m,are dropped from the top of a building.When they hit the ground

If electricity costs 6.00¢/kWh (kilowatt-hour),how much would it cost you to run a 120 W stereo system 4.0 hours per day for 4.0 weeks?

An object is acted upon by a force that represented by the force vs.position graph in the figure.What is the work done as the object moves (a)from 4 m to 6 m? (b)from 6 m to 12 m?

A worker lifts a 20.0-kg bucket of concrete from the ground up to the top of a 20.0-m tall building.The bucket is initially at rest,but is traveling at 4.0 m/s when it reaches the top of the building.What is the minimum amount of work that the worker did in lifting the bucket?