physics

 the following questions ask you to solve problems involving topics we've covered this week. Work each problem on paper, and post a scanned image of your work for each question, along with a brief description of how you solved the problem. Your scanned work should include a step-by-step solution to the problem. Upload your work to the same W4 Assignment 2 Lab Dropbox.

Question 1  

A person pulls a crate with 120 N of force against 100 N of friction a distance of 5 meters. Sketch a free body diagram showing the forces acting on the crate and find the energy the person expends pulling the crate, the amount of energy converted to heat via friction, and the increase in the kinetic energy of the crate.

Question 2  

A box of mass 4 kg is resting on a table 1.5 m above the floor. There is also a ledge located 5 m above the floor. First, provide a sketch of this problem. Then, find the gravitational potential energy of the box relative to the floor, and the gravitational potential energy of the box relative to the ledge.

Question 3  

An 80 kg man climbs a 50 m-high hill in 20 minutes. What is the average power in watts he expends climbing the hill?

Question 4  

A 40,000 kg railroad car initially traveling at 10 m/s collides inelastically with a 20,000 kg railroad car intially at rest. The cars stick together. What is their final speed?

Question 5  

A roller coaster is initially at a height of 40 m above the ground and has an initial velocity of 15 m/s. Using conservation of energy, find the velocity of the roller coaster at a height of 5 m above the ground. Sketch the problem before you solve it.