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Period 9 Exercises
E.1
Joe weighs 900 N.
He runs up a flight of
steps in 3 seconds and stops on a landing a
distance of 2 meters above ground level.
How much power did Joe supply in doing
work against gravity while climbing the
stairs?
a)
37.5 watts
b)
600 watts
c)
1350 watts
d)
2160 watts
e)
3600 watts
E
pot
=
M g h
=
900 N
x
2 m
=
1,800 J
P
=
E
=
1,800 J
=
600 J/s
=
600 W
t
3
s
E.1
=
b
9-Ex 1

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*Sign up* E.2
Suppose you climb a 10 ft. stairway in 3
seconds and then you climb a 20 ft.
stairway in 6 seconds. Which of the
following statements about the work done
against the force of gravity and the power
required for this work is
TRUE?
a)
You used
twice as much energy
and
required
twice as much power
to climb
the 20 ft. stairway as you did to climb
the 10 ft. stairway.
b)
You used
twice as much energy
but
required the
same amount of power
to
climb the 20 ft. stairway as you did to
climb the 10 ft. stairway.
c)

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