Exam 7: Energy of a System

Two eggs of equal mass are thrown at a blanket with equal velocity.Egg B hits the blanket but egg A hits the wall instead.Compare the work done on the eggs in reducing their velocities to zero.

A 10-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 1.2 kN/m).The block is initially at rest at its equilibrium position when a force (magnitude P)acting parallel to the surface is applied to the block,as shown.When the block is 8.0 cm from the equilibrium position,it has a speed of 0.80 m/s.How much work is done on the block by the force P as the block moves the 8.0 cm?

A constant force of 15 N in the negative y direction acts on a particle as it moves from the origin to the point m.How much work is done by the given force during this displacement?

Two vectors And Are given by And )The scalar product of And a third vector Is −16.The scalar product of And Is +18.The z component of Is 0.What is the magnitude of ?

A 2.5-kg object falls vertically downward in a viscous medium at a constant speed of 2.5 m/s.How much work is done by the force the viscous medium exerts on the object as it falls 80 cm?

A 10-kg block on a rough horizontal surface is attached to a light spring (force constant = 1.4 kN/m).The block is pulled 8.0 cm to the right from its equilibrium position and released from rest.The frictional force between the block and surface has a magnitude of 30 N.What is the kinetic energy of the block as it passes through its equilibrium position?

A 10-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 0.80 kN/m).The block is initially at rest at its equilibrium position when a force (magnitude P = 80 N)acting parallel to the surface is applied to the block,as shown.What is the speed of the block when it is 13 cm from its equilibrium position?

If the scalar product of two vectors, And ,is equal to −3.5,if ,and the angle between the two vectors when they are drawn starting from the same point is equal to 130°,what is the magnitude of ?

A 2.0-kg projectile moves from its initial position to a point that is displaced 20 m horizontally and 15 m above its initial position.How much work is done by the gravitational force on the projectile?

Two clowns are launched from the same spring-loaded circus cannon with the spring compressed the same distance each time.Clown A has a 40-kg mass;clown B a 60-kg mass.The relation between their speeds at the instant of launch is

Two vectors And Are given by And )If these two vectors are drawn starting at the same point,what is the angle between them?

A 2.0-kg particle has an initial velocity of m/s.Some time later,its velocity is m/s.How much work was done by the resultant force during this time interval,assuming no energy is lost in the process?

The graph below shows how the force on a 0.500 kg particle varies with position.If the particle has speed At x = 0.00 m,what is its speed in m/s when x = 8.00 m?

Equal amounts of work are performed on two bodies,A and B,initially at rest,and of masses M and 2M respectively.The relation between their speeds immediately after the work has been done on them is

Two clowns are launched from the same spring-loaded circus cannon with the spring compressed the same distance each time.Clown A has a 40-kg mass;clown B a 60-kg mass.The relation between their kinetic energies at the instant of launch is

The same constant force is used to accelerate two carts of the same mass,initially at rest,on horizontal frictionless tracks.The force is applied to cart A for twice as long a time as it is applied to cart B.The work the force does on A is W_A;that on B is W_B.Which statement is correct?

A block slides on a rough horizontal surface from point A to point B.A force (magnitude P = 2.0 N)acts on the block between A and B,as shown.Points A and B are 1.5 m apart.If the kinetic energies of the block at A and B are 5.0 J and 4.0 J,respectively,how much work is done on the block by the force of friction as the block moves from A to B?

A 30-kg child sitting 5.0 m from the center of a merry-go-round has a constant speed of 5.0 m/s.While she remains seated in the same spot and travels in a circle,the work the seat performs on her in one complete rotation is

Two balls,A and B,of mass m and 2m respectively,are carried to height h at constant velocity,but B rises twice as fast as A.The work the gravitational force does on B is

If , ,and ,what is the angle between the two vectors when they are drawn starting from the same point?