A dog in a weight-pulling competition tugs a 50-kg sled adistance of 5 m across a snowy track. The dog pulls horizontallywith a force of 350 N. The coefficient of kinetic friction betweenthe sled and the snow is 0.05. (Draw yourself a free-body diagramon the sled). The next four questions have to do with thisscenario.

Determine the work done by the dog.

I got the correct work (1750J)

Add up the y-components, ΣF_y, and determine thenormal force the ground exerts upward on the sled.

Using your result from above, calculate the kinetic frictionalforce between the sled and the snowy track.

Determine the work done by friction.

A daring 51-kg swimmer dives off a 9-m high cliff. At the edgeof the cliff her speed is 1.5 m/s. As the swimmer travels throughthe air, air resistance does -900 J of work on her. The next threequestions have to do with this swimmer.

Which is the correct conservation of energy expression for thisdiving swimmer?

Using the appropriate conservation of energy expression,determine the kinetic energy of the swimmer as she safely entersthe water at the bottom of the cliff.

Using your result from above, determine the swimmer's speed asshe enters the water.

A 1.5-kg ball rolling to the right at a speed of 3 m/s collideswith another ball of mass 3.0 kg rolling to the left at a speed of2 m/s. As a result of the collision, the 1.5-kg ball recoils to theleft at a speed of 1.5 m/s. (Draw yourself a before & afterpicture of this collision).  The next five questions haveto do with this collision.

Calculate the momentum (magnitude and direction) of the 1.5-kgball immediately before the collision.

Calculate the momentum (magnitude and direction) of the 3.0-kgball immediately before the collision.

Calculate the momentum (magnitude and direction) of the 1.5-kgball immediately after the collision.

Set up the conservation of momentum for this collision anddetermine the velocity (magnitude and direction) of the 3.0-kg ballimmediately after the collision.

After the collision, the system's total kinetic energy is