Each question is section 1 is worth 2 points, there are 14 questions. Section 2.
1A) Which of the following is a unit of energy:
a. watt
b. ft-lb/sec
c. newton/sec.
d. horsepower
e. joule
1B). If a constant nonzero net force is applied to a book, what can you say about the acceleration of the book?
a. increases
b. constant
c. decreases
d. becomes zero
1C) Which of the following is a non-renewable resource?
a. uranium
b. water
c. wind
d. radiant solar
1D). Work done in completing a task is equal to
a. mass x acceleration
b. mass x distance
c. force x distance
d. force x distance/time
1E). A pendulum of a clock swings back and forth. At what position of the trajectory of the bob will the kinetic energy be the greatest?
a. at its highest point
b. at its lowest point
c. halfway between the two
d. it is always zero
1F) The "efficiency" of a light bulb is the ratio of the:
a. heat plus electricity produced to the electrical input
b. voltage output of the bulb to the power input
c. energy into the bulb to the energy out of the bulb
d. light output to the electrical energy input
1G) When a car is braked to a stop, its kinetic energy is transformed into
a. stopping energy
b. potential energy
c. heat energy
d. energy of motion
1H) If the push that you give to a bike is the action force, then the reaction force is ________.
a. the weight of the bike
b. the friction force on the tire
c. the force of the bike upon you
d. the acceleration of the bike
e. air resistance on the bike
1(I). Heat is ________.
a. a measure of the average kinetic energy of molecules in an object
b. a property of an object
c. the energy transferred between bodies due to a temperature difference
d. the specific heat of an object
1J). When heat is added to an object, the temperature
a) always decreases
b) always increases
c) may remain constant
d) has nothing to do with heat
1(K). Heat energy will spontaneously always flow in the direction of ________ .
a. a higher temperature
b. a lower temperature
c. up, since heat rises
d. a smaller heat capacity
1L). Your feet feel warmer on a rug than on a tile floor because the rug
a. is usually warmer than the tile
b. is a better insulator than tile
c. has more internal energy than tile for the same mass
d. all of these
1M). An object with a high specific heat will ________.
a. lose its heat very fast
b. decrease in temperature quite fast if removed from the heat source
c. take considerably more heat to raise its temperature
d. always be water
1N). If the average rate of sunshine per square meter is 1300 W/m2 striking the top of the atmosphere and 35% bounces off the atmosphere, how much is left per square meter to strike the Earth?
a) 1045 W/m2
b) 845 W/m2
c) 485 W/m2
d) 0 W/m2
For the following questions, if the answer requires a derivation, clearly show the equations, the calculation and units . Use your own paper and not the space between the problems.
2). A car of 1600 Kg goes from 0 to 100 km/hour in 6.2 seconds. What is the net force acting on the car?
3). What is the kinetic energy, in Joules, of a car of mass1,200 kg moving at 36 m/s?
4). A 8 kg cannonball is launched vertically with a kinetic energy of 30,000 joules. How high will it get before it turns around, assuming no energy losses due to air resistance? Express your answer in meters.
5). What is the net force responsible for the acceleration if a 60 kg person is observed to accelerate at a rate of 4 m/sec2).
6). What is the difference between energy and power? What is the difference between mass and weight? Elaborate with units.
7). If a 1000 -MW power plant is shut down for one day, what will be the loss in revenue in the utility company could sell it electricity for 12c/ kW-hr?
8). What is the maximum efficiency of a heat engine operating between 20C and 2000C? Remember to first convert the temperatures to degree Kelvin.
9). Calculate the amount of heat required to raise the temperature of 200 gm of water from 200 C to 1000 C. (Use Q = m cΔT where c is 4.184 J/g 0C. )
10). How much energy will it take to melt a block of ice of mass 15 Kg?
11) Explain the first and second law of thermodynamics?
12.) Calculate the Carnot efficiency of a heat engine that has a temperature of 1200 K brought down to 150 K. If this same engine turns 500J of input energy into 375 J of useful work what is it's efficiency? Considering the Carnot efficiency, what would be the maximum amount of useful work you could get from that 500J? What is the loss between the Carnot efficiency and the actual efficiency? (8 marks)
13). What wavelength of electromagnetic radiation would you expect from a radio station broadcasting at 120 MHz?