| |
Chap. 14
Voc. (26)
S.B. 2, 3, 4 and 6
Essay 2, and 4
Essay Questions-
2. Why does the winner in a swimming race have the most power?
4. Explain how machines make work easier. Use several examples in your
answer.
Skill Building:
2. Two boys each weigh 800 newtons. One boy climbs a 5.0 meter rope on 10.0
seconds. The other boy climbs the same rope in 8.0 seconds.
a. How much work is done by each boy?
b. What is the power in watts of each boy?
c. What is the horsepower of each boy?
Hint: 1hp= 746 watts
3. Applying Formulas: The work output of the pulley is 900 joules. The work
input is 1000 joules. What is the efficiency of the pulley? How could you
increase the efficiency of the pulley?
6. Relating Concepts: Suppose you live on a fifth floor of an apartment
building . You have just bought a new tape deck that weighs 50 newtons. To
reach your apartment, which is 35 meters up, you can climb the stairs or take
an elevator.
a. If you climb the stairs, how much work do you do?
b. If you take the elevator, is the amount of work greater, smaller, or
equal to the work done in part a?
c. If it takes you five minutes to climb up the stairs, what is your
power? Remember, the time unit for power is seconds.
d. Compare your power with that of the elevator if it takes two minutes
for the elevator to reach the fifth floor.
|
|