1)

1) Make up an example of an energy transformation that involves several forms of energy. Write out the energy transformation equation for your example.

2) State the SI unit used to measure

(a) Work (b) Kinetic energy (c) Power

3) A black bear’s greatest enemy is the grizzly bear. To escape grizzly’s attack, a black bear does what its enemy cannot do- it climbs a tree whose truck has a small diameter. Calculate the work done by a 140kg black bear in climbing 18m up a tree.

4) Compare the amount of work you would do in climbing a vertical rope with the work done in climbing a stairway inclined at 45º, if both activates get you 6 m higher.

5) A golf ball is given 115J of energy by a club that exerts a force over a distance of 4.5cm while the club and ball are in contact.

(a) Calculate the magnitude of the average force exerted by the club on the ball.

(b) If the ball’s mass is 47g, find the magnitude of its average acceleration.

6) A roast of beef waiting to be taken out of a refrigerator’s freezer compartment has a potential energy of 35J relative to the floor. If the roast is 1.7m above the floor, what is the mass of the roast?

7) A 55kg diver has 1.62kJ of gravitational potential energy relative to the water when standing on the edge of a diving board. How high is the board above the water?

8) A group of winter enthusiasts returning from the ski slopes are travelling at 95km/h along a highway. A pair of ski boots having a total mass of 2.8kg has been placed on the shelf of the rear window.

(a) What is kinetic energy of the pair of boots?

(b) What happens to that energy if the driver must suddenly stop the car?

9) What happens to an object’s kinetic energy when its speed doubles? triples?

10) A 50kg cyclist on a 10kg bicycle speeds up from 5m/s to 10m/s.

(a) What is the total kinetic energy before accelerating?

(b) What is the total kinetic energy after accelerating?

(d) Is it more to speed up from 0 to 5m/s than from 5m/s to 10m/s? Explain.

11) A discus travelling at 20m/s has 330J of kinetic energy. Find the mass of the discus.

12) An archer nocks a 0.20kg arrow on a bowstring. Then the archer exerts an average force of 110N to draw the string back 0.6m. Assume that friction is negligible.

(a) What speed does the bow give to the arrow?

(b) If the arrow is shot vertically upward, how high will it rise?

13) It is possible to heat a cold kitchen by opening the oven door, but it is not possible to cool the kitchen by opening the refrigerator door. Why?

14) Some people perform difficult tasks to raise money for charity. For example, walking up the stirs in Toronto’s CN Tower helps both charity and personal fitness. Assume that the efficiency of the human body is 25%. If a 70kh participant climbs the 342m height of the tower 10 times in 4h, calculate the following:

(a) the work the participant does against the force of gravity on each trip up the stairs

(b) the energy the participant’s body require for each trip up the stairs (including wasted energy)

(d) the power of the participant’s body for the upward trips

15) Explain why it is impossible to have a motor that is 100% efficient.

16) State the method of heat transfer

(a) that does not require particles

(b) that works because particles collide with their neighbours

(e) that works when particles circulate in a path

17) Given an equal mass of aluminium and brass, which mass would require more heat if the temperature of both were raised the same number of degrees?

18) How much heat is required to raise the temperature of 2kg of water from 25ºC to 83ºC?

19) What will be the temperature change in each of the following?

(a) 10kg of water loses 456kJ

(b) 4.8kg of alcohol gains 12.6kJ

20) A 6g pellet of lead at 32ºC gains 36.8J to heat. What will be its final temperature?

21) When 2.1 x 10³J to heat is adder to 0.1kg of a substance, its temperature increases from 19ºC to 44ºC. What is the specific heat capacity to the substance?

22) How much water at 82ºC must be added to 0.2kg of water at 14ºC to give a final temperature of 36ºC?

23) When 0.5kg of water at 90ºC is added to 1kg of water at 10ºC, what is the final temperature?

24) A waterfall is 55m high. If all the gravitational potential energy of the water at the top of the falls were converted to thermal energy at the bottom of the falls, what would be the increase in the temperature of the water at the bottom? (Hint: Consider one kilogram of water going over the waterfall.)

25) Calculate the power of a light bulb that transforms 1.5 x 10⁴J of energy per minute.

26) How much energy is transformed by a 1200w electric kettle during 5min of operation?

27) An alternative unit of the to the joule or megajoule is the kilowatt hour (kW·h), which is used in many parts of Canada to measure electrical energy. One kilowatt hour is equivalent to one kilowatt of power used for one hour. Prove that 1 kW·h= 3.6 MJ.

28) Use the law of conservation of energy to derive an expression for the speed v acquired by an object allowed to fall freely from rest through a height h at a location where the gravitational field strength is of magnitude g. Assume that air resistance can be ignored.

29) A child of mass m slides down a slide 5m high. The child’s speed at the bottom of the slide is 3m/s.

(a) What percent of the mechanical energy that the child has at the top of the slide not converted to kinetic energy?

(b) What feature of the slide determines the percentage of mechanical energy that is converted to other forms of energy?

30) A chair lift takes skiers to the top of a mountain that is 320m high. The average mass of a skier complete with equipment is 85kg. The chair lift can deliver three skiers to the top of the mountain every 35s.

(a) Determine the power required to carry out this task. (Assume the skiers join the lift at full speed.)

(b) If friction increases the power required by 25%, what power must the motors running the lift be able to deliver?

32) In winter the ground may be frozen, but large bodies of water such as the Great Lakes usually are not. Why?

35) The topic of physics in sports has many areas for further exploration.

(a) Choose a sport to research. Analyze the improvements in the performance of the athletes of that sport due to the application of physics principles and concepts and present your findings. Consider ideas related to work, kinetic energy, potential energy, and the law of conservation of energy. Follow the links for Nelson Physics 11, Chapter Review. Go To: www.science.nelson.com

(b) Describe issues other than the physics principles that you find in your research.

1) Discuss reasons why Canada’s rate of energy consumption is much higher than the world average.

2) If the cost of natural gas increases at 3.6%/a, by what factor will the price have increased after

(a) 20 a? (b) 40 a? (c) 100 a?

3) Assume that our federal government wants to be sure that 50 years will elapse before the number of cars in Canada doubles.

What growth rate per annum should the government advocate?

7) Metal cooking pots can be made totally of aluminium or with aluminium sides and copper bottoms. (Copper is better heat conductor than aluminium.) A chef puts 1.5kg of 15ºC water into an all-aluminium pot, which is then placed on a stove burner rated at 1.8kW. The water takes 6min 25s to reach the boiling point, at which time the chef adds the pasta and some salt.

(a) Determine the efficiently of the stove burner in heating the water to the boiling point.

(b) Where does the wasted energy go?

8) What is a fossil fuel? What are its main components?

10) State the main advantages and main disadvantages of using each of the following non- renewable energy resources:

(a) oil (b) natural gas (c) coal (d) tar sands (e) uranium

11) State the main advantage and main disadvantage of each of the following renewable energy resources:

(a) solar energy (b) hydraulic energy (c) wind (d) tides

(e) biomass (f) geothermal energy (g) nuclear fusion

(h) the atmosphere

16) Engineers have long dreamed of harnessing the tides in the Bay of Fundy. Although in some places the difference between high tide and low tide can be over 15m, the average change in height for the entire bay is about 4m. The bay has the same area as a rectangle that is about 3 x 10²km long and 65km wide. Wather has a density of 1 x 10³kg/m³.

(a) Calculate the volume of water and the mass of water that flows out of the bay between high tide and low tide.

(b) Determine the loss in gravitational potential energy when the water flows out of the bay. Assume that the decrease in gravitational potential energy is equal to that of the mass calculated in (a) being lowered a distance of 2m.

(c) In half the gravitational potential energy lost when the tide flows out could be converted to electricity over a 6h period, determine the amount of electrical power that would be generated.