Transcript Units & Measurement

Power
“A powerful athlete is not a strong athlete, but
one who can exert his strength quickly. Since
power equals force times speed, if the athlete
learns to make faster movements he increases
his power, even though the contractile pulling
strength of his muscles remains unchanged.
Thus, a smaller man who can swing faster may
hit as hard or as far as the heavier man who
swings slowly.”
Power
Problems
1) Convert 30 ft/sec into mi/hr
2) Convert 12 lbs/in into kg/m
3) Two people of the same mass climb the same height of
stairs. The first person climbs the stairs in 25 seconds; the
second person takes 35 seconds.
a) Which person does more work? Explain.
b) Which person produces more power? Explain.
Problems
5. A student applies a force of 32 N to push a laboratory
cart down the hall for 18 m. How much work does the
student do?
6. A teacher lifts a 22 kg box of books off the floor and
places it on a lab station that is 0.95 m high. How much
work did the teacher do?
Problems
7. If the teacher in #6 lifted the box of books in 0.37
seconds, how much power did she demonstrate?
8. An weightlifter lifts a 75 kg barbell a distance of 2.2 m in
0.15 s. How much power is demonstrated by the lift?
Technology
Tools
-phillips head screwdriver
-flat head screwdriver
-nail
-screw
-bolt
-nut
-washer