Hello please answer each question by step - step and provide the solutions to. 9. An experiment is performed to determine the power of an electric hoist that is used to lift bricks to the top of a scaffold at a constant speed. What quantities would need to be measured to calculate the power of the hoist? a. number of bricks, speed of the lift, time taken b. number of bricks, distance traveled, time taken C. mass of bricks, distance traveled, time taken d. mass of bricks, time taken 10. Which combination of light bulbs and operating times would consume the same quantity of energy as six 100-W light bulbs operating for 1.0 h? a. eight 60-W light bulbs operating for 1.0 h b. ten 50-W light bulbs operating for 1.2 h C. two 150-W light bulbs operating for 2.5 h d. one 300-W light bulb operating for 1.8 h 11. The efficiency of an energy transformation is a measure of a. the quantity of work done or energy converted b. the rate of doing work or transforming energy C. how much useful work is done or energy transformed d. how much work is done compared with how much energy is required to do the work 12. If the efficiency of an energy transformation is 0.40 a. over half the energy being used is wasted b. the percent efficiency is 40% c. only 4 units of intended energy output occur for every 10 units of energy imput d. all of the above 13. If a person does 2.0x103 J of work in raising a 65-kg object through a distance of 3.0 m using a pulley, the percent efficiency of this machine is: a. 96% b. 32% c. 9.8% d. 0.96% 14. Which of the following would not be considered to be a heat engine? a. jet engine b. large electric motor C. gasoline engine d. steam turbine 15. What is the proper sequence of a four-stroke engine following the intake stroke? a. compression, exhaust, power b. power, compression, exhaust C. compression, power, exhaust d. power, exhaust, compression 16. In a four-stroke, reciprocating engine a. the piston goes through two cycles during the four strokes b. the piston goes through one cycle during the four strokes c. the piston goes through four cycles during the four strokes d. the piston goes through four cycles during each stroke 17. The percent efficiency of two-stroke and four-stroke gasoline engines is a. less than 20% b. between 20% and 40% c. between 40% and 60% d. over 60% 18. Concerning the operation of a four-stroke engine, the intake and exhaust valves are closed during a. the power stroke only b. the intake stroke only c. the exhaust stroke only d. both the compression and power strokes 19. Which of the following is not true about two-stroke engines? a. they can be either gasoline-powered or diesel fuel-powered b. they utilize ports rather than valves, unlike their four-stroke counterparts c. they have a very similar efficiency compared with four-stroke engines d. their pistons are designed so that fuel and exhaust gases never mix 20. The energy flow diagram above illustrates the conversion of electrical energy into light energy. If this conversion is 42% efficient, how much waste heat energy is generated? a. 74J b.30 J C.361 d. 26 J Part B (Putting the Concepts to Work): Completion: Using your reading, answer the following questions. Give your answer as well as your strategy for determining your answer. As part of your answer, give the page number in the reference material or the website that you used to find the answer to the question. 21. A weightlifter transforms 2.0 kJ of energy in 3.0 s. What is the weightlifter's power? 22. How much energy does a 60.0 W-light bulb transform in 1.0 h? 23. What power is required to lift a textbook (m = 1.2 kg) from the floor to the desktop, a distance of 80.0 cm, if it takes 1.3 s to complete the lift? 24. A simple pulley is used to lift a 185-kg crate a vertical distance of 3.3 m. Two people exert a combined force of 2.0 x 103 N on the other end of the rope. a. What is the percent efficiency of the pulley? b. Draw the energy flow diagram for this situation 25. The energy flow diagram pictured above represents a particular energy transformation. Determine its efficiency.

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