# essay question

Exam 1 consist of five essay questions to solve. Use the space in the essay box to show how you completed each calculation.

1. While traveling along a level highway at a speed of 27 m/s (60 miles per hour), you shift the vehicle into neutral and find that it takes 4.5 seconds to slow to 20 m/s (45 miles per hour.) Include in your response:

a) What is the deceleration of your vehicle during these 4.5 seconds?

b) What force is applied by the air resistance acting on the car, assuming the mass of the car

to be 2000 kg?

2. A 40-kg child runs at 8 m/s.

a) Calculate the child’s kinetic energy.

b) If the child could convert all of the kinetic energy you calculated in part (a), into upward motion, how high could she jump?

3. Calculate the overall efficiency to produce light in a fluorescent lamp from electrical energy derived from a nearby nuclear power plant. This multistep process begins with the efficiency of a nuclear power plant, rated at 35%; then the electrical energy is transmitted over transmission lines rated at 90%, and finally the electrical energy used by the fluorescent bulb to produce light, rated at 20%. In your response, show your work so that you can receive some partial credit. (Points : 10)

4 How much electrical energy is needed to heat the water in a hot water heater with a capacity of 40 gallons from 60°F to 110°F? How much will this cost at a rate of $0.13/kWh? Show your work and make sure to answer both questions. (Points : 10)

5. What is the efficiency of an engine that has 2200 J of heat added during combustion and loses 1000 J of heat in the exhaust? (Points : 10)