Assignment:
1.) A 493.0 g pot of water at room temperature (20.0°C) is place on a stove. How much heat is required to change this water to steam at 100.0°C?
2.) A 1.2 kg metal head of a geology hammer strikes a solid rock with a speed of 3.7 m/s. Assuming all the energy is retained by the hammer head, how much will its temperature increase?
3.) The driver of a 850.0 kg car decides to double the speed from 21.4 m/s to 42.8 m/s. What effect would this have on the amount of work required to stop the car, that is, on the kinetic energy of the car?
4.) What is the horsepower of a 1,500.0 kg car that can go to the top of a 380.0 m high hill in exactly 1 minute?
5.) (a) How many seconds does it take a 27.5 hp motor to lift a 2,500.0 lbelevator a distance of 90.0 ft? answer must be given in seconds.
(b) What was the average velocity of the elevator?
6.) (a) What is the kinetic energy of a 2,030 kg car that is traveling at 98.0 km/h?
(b) How much work was done to give the car this kinetic energy, assuming that the car starts from rest?
(c) How much work must be done to stop the car?
7.) A 147.0 g baseball has a velocity of 31.7 m/s. What is its kinetic energy in J?
How much work is needed to stop a 1,570 kg car that is moving straight down the highway at 57.0 km/h?
8.) Enter your answer in scientific notation. What is the kinetic energy of a 2,400 kg car moving at 88 km/h?
9.) In an electric freezer, 319.0 g of water at 25.9°C is cooled, frozen, and the ice is chilled to -6.0°C. (a) What is the change of heat in the water? Answer must be given in kcal (b) If the latent heat of vaporization of the Freon refrigerant is 40 cal/g, how many grams of Freon must be evaporated to absorb this heat?
10.) A 68.3 kg student runs up the stairs of a football stadium to a height of 10.8 m above the ground in 11.0 s. (a) What is the power of the student in kW? (b) in hp?
(a) P= ____kW
(b) P=____ hp
11.) A refrigerator removes 27.0 kcal of heat from the freezer and releases 73.5 kcal through the condenser on the back. How much work was done by the compressor?
12.) How many minutes would be required for a 327.0 W immersion heater to heat 217.0 g of water from 20.6°C to 88.1°C?
13.) A 50.2 kg person will need to climb a 2.7 m stairway how many times to "work off" each excess Cal (kcal) consumed?
14.) A bicycle and rider have a combined mass of 109.0 kg. How many calories of heat are generated in the brakes when the bicycle comes to a stop from a speed of 31.9 km/h?
15.) An electrical current heats a 245 g copper wire from 16.8°C to 35.4°C. How much heat was generated by the current?