In: Physics
A dog in a weight-pulling competition tugs a 50-kg sled a distance of 5 m across a snowy track. The dog pulls horizontally with a force of 350 N. The coefficient of kinetic friction between the sled and the snow is 0.05. (Draw yourself a free-body diagram on the sled). The next four questions have to do with this scenario.
Determine the work done by the dog.
I got the correct work (1750J)
Add up the y-components, ΣFy, and determine the normal force the ground exerts upward on the sled.
Using your result from above, calculate the kinetic frictional force 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 edge of the cliff her speed is 1.5 m/s. As the swimmer travels through the air, air resistance does -900 J of work on her. The next three questions have to do with this swimmer.
Which is the correct conservation of energy expression for this diving swimmer?
Using the appropriate conservation of energy expression, determine the kinetic energy of the swimmer as she safely enters the water at the bottom of the cliff.
Using your result from above, determine the swimmer's speed as she enters the water.
A 1.5-kg ball rolling to the right at a speed of 3 m/s collides with another ball of mass 3.0 kg rolling to the left at a speed of 2 m/s. As a result of the collision, the 1.5-kg ball recoils to the left at a speed of 1.5 m/s. (Draw yourself a before & after picture of this collision). The next five questions have to do with this collision.
Calculate the momentum (magnitude and direction) of the 1.5-kg ball immediately before the collision.
Calculate the momentum (magnitude and direction) of the 3.0-kg ball immediately before the collision.
Calculate the momentum (magnitude and direction) of the 1.5-kg ball immediately after the collision.
Set up the conservation of momentum for this collision and determine the velocity (magnitude and direction) of the 3.0-kg ball immediately after the collision.
After the collision, the system's total kinetic energy is