- is the rate of doing work
-refers to how much work is done in certain amount of time
if the work done is due to an applied force the equation can be written as
P= W = F d
t t
If the work done is due to gravity, the equation is
P= mgh
t
What is the average power of an elevator
if it takes 100,000 J lift it 24 m in 25s?
G-
U-
E-
S
S
Isay used 150 N of horizontal force to move
a box from the corner of the classroom to a distance of 4.5 m to the right. It took her 56s to
finish the work. Kiko pushed an identical box
using the same amount of force toward the same
position.It took hm 48 s to do it. Compare the power of Isay and kiko in pushing the box.
Isay:
G= f- 150N d= 4.5m t= 56
U= P?
E= Fd
t
S= (150)(4.5)
56
S= 12.1 J/s or Watt
say:
G= f- 150N d= 4.5m t= 48
U= P?
E= Fd
t
S= (150)(4.5)
48
S= 14.1 J/s or Watt