Exam 7: Kinetic Energy and Work

A block is attached to the end of an ideal spring and moved from coordinate x_i to coordinate x_f.The relaxed position is at x = 0.The work done by spring is positive if:

A 4-kg cart starts up an incline with a speed of 3 m/s and comes to rest 2 m up the incline.The total work done on the cart is:

Camping equipment weighing 6000 N is pulled across a frozen lake by means of a horizontal rope.The coefficient of kinetic friction is 0.05.How much work is done by the campers in pulling the equipment 1000 m if its speed is increasing at the constant rate of 0.20 m/s²?

A particle moving along the x axis is acted upon by a single force F = F₀e^-kx, where F₀ and k are constants.The particle is released from rest at x = 0.It will attain a maximum kinetic energy of:

A watt per hour is a unit of:

A boy holds a 40-N weight at arm's length for 10 s.His arm is 1.5 m above the ground.The work done by the force of the boy on the weight while he is holding it is:

An ideal spring is hung vertically from the ceiling.When a 2.0-kg mass hangs at rest from it, the spring is extended 6.0 cm from its relaxed length.An upward external force is then applied to the block to move it upward a distance of 16 cm.While the block is being raised by the force, the work done by the spring is

A particle starts from rest at time t = 0 and moves along the x axis.If the net force on it is proportional to t, its kinetic energy is proportional to:

The plot shows the force on an object as it moves from x = 0 m to x = 20 m.How much work is done on the object?

An object of mass 1 kg is whirled in a horizontal circle of radius 0.5 m at a constant speed of 2 m/s.The work done on the object during one revolution is:

An escalator is used to move 20 people (60 kg each)per minute from the first floor of a department store to the second floor, 5 m above.The power required is approximately:

The work done by gravity during the descent of a projectile is:

A baseball is hit high into the upper bleachers of left field.Over its entire flight the work done by gravity and the work done by air resistance, respectively, are:

An 80-N crate slides with constant speed a distance of 5.0 m downward along a rough slope that makes an angle of 30 $\degree$ with the horizontal.The work done by the force of gravity is:

A line drive to the shortstop is caught at the same height as it was originally hit.Over its entire flight the work done by gravity and the work done by air resistance, respectively, are:

A woman lifts a barbell 2.0 m in 5.0 s.If she lifts it the same distance in 10 s, the work done by her is:

A 0.50-kg object moves in a horizontal circular track with a radius of 2.5 m.An external force of 3.0 N, always tangent to the track, causes the object to speed up as it goes around.The work done by the external force as the mass makes one revolution is:

At time t = 0 a 2-kg particle has a velocity of (4 m/s)- (3 m/s).At t = 3 s its velocity is (2 m/s)+ (3 m/s).During this time the work done on it was:

The mechanical advantage of any machine is:

A 100-kg piano rolls down a 20° incline.A man tries to keep it from accelerating, and manages to keep its acceleration to 1.2 m/s².If the piano rolls 5 m, what is the net work done on it by all the forces acting on it?