Exam 6: Potential Energy and Energy Conservation

You are on a sled at the top of a 30.0-m tall toboggan run.Provided you can ignore friction forces between the sled and the track,when you reach the bottom of the toboggan you have a speed of

A projectile of mass 2.00 kg is launched from the ground with a speed 10.0 m/s at an angle 20.0 ^$\circ$ above the horizontal.Assume that air drag is negligible.What is the kinetic energy of the projectile 0.500 seconds after it is launched?

The potential energy of an object as a function of position is U(x)= x² - x - 6,where U is measured in joules and x is measured in meters.Where is the object be located if it is in a stable equilibrium?

A spring,with k = 2500 N/m,is fixed vertically to the floor.A 10.0-kg box is pressed down on the spring such that the total compression of the spring is 0.5 m.When the box is released,what is the maximum speed the box reaches?

On a snowy day your car which is moving at 20 km/h skids 15 m with locked brakes.When moving at 120 km/h with locked brakes,your car would skid

A tennis ball of mass 70 g is thrown vertically upward at 25 m/s.It rises to a height of 21 m.The work done by the resistive forces is

I push an object along a horizontal surface a distance d with a force F at an angle .If the velocity is constant at a value v,then

A spring,with k = 2500N/m,is fixed vertically to the floor.A 10.0-kg box is then pressed down such that the spring is compressed 0.5 m beyond its equilibrium length.The box is then released.Assuming the work done against drag (air resistance)is 60 J,how high will the box travel above its release position?

The potential energy of an object as a function of position is U(x)= x³ - 12x + 8,where U is measured in joules and x is measured in meters.Where is the object be located if it is in an unstable equilibrium?

The mechanical energy of an object is always equal to

A 1.0-kg object 2.0 m above the floor has a gravitational potential energy of 3.0 J.How much gravitational potential energy does the object have when it is 4.0 m above the floor?

A body fired vertically up reaches a maximum height of 120 m.The location at which the kinetic energy is 75% of the potential energy is

A 30.0-kg crate is pushed across a rough floor by a horizontal force of 100 N.The coefficient of kinetic friction between the crate and the floor is 0.100.If a total of 80.5 J of work is done on the crate,how far was it moved along the floor?

A 60-kg man needs to climb a flight of stairs 25 m high at a constant speed.The energy he requires is

A sled of mass 10 kg starts out at an initial speed of 5 m/s on a horizontal surface.The coefficient of kinetic friction with the snow is 0.05.Use energy considerations to determine how far it goes before it comes to a stop (within 5% accuracy).

441 J of work is required to slide a 15-kg ice block up a frictionless slope that is 20 m long.The incline of the slope with respect to horizontal is

A 20.0-kg object starts from rest and slides down an inclined plane.The change in its elevation is 2.50 m and its final speed is 5.00 m/sec.How much energy did the object lose due to friction as it slid down the plane?

A mortar launches a 8.50-kg fireworks shell straight up with an initial speed of 62.6 m/s.How high does the shell go?

An Olympic weight lifter lifts a 186 kg weight from the floor to a height of 2.10 m.The change in the potential energy of the weight is

A block (m=12 kg)is moving at a speed of 7.0 m/s on a level surface.A force of 25 N is applied in the direction that it is moving but it comes to a stop in a distance 625 cm.Find the coefficient of friction.