**Need Help-Physics Assignment**

- 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? answer must be given in kcal
- 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? (chead = 0.11 kcal/kg°C). answer must be given in °C

- 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?

KEi=__× 10^5 J

KEf=__ × 10^5 J

___times as much work must be done to stop 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 lb elevator a distance of 90.0 ft? answer must be given in seconds.

(b) What was the average velocity of the elevator? Answer must be given in ft/s

6.) (a) What is the kinetic energy of a 2,030 kg car that is traveling at 98.0 km/h? answer must be given in kJ

- b) How much work was done to give the car this kinetic energy, assuming that the car starts from rest? Answer must be given in kJ

(c) How much work must be done to stop the car? Answer must be given in kJ

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? answer must be given in scientific notation

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? Answer must be given in g.

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

- 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? Answer must be given in KJ
- 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? answer must be given in min
- 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?

- 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? answer must be given in kcal
- (copper = 0.093 cal/g°C) 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? Answer must be given in cal

**Need Help-Physics Assignment**