Download Power - Cobb Learning

Horses Have It…
Power
Review: What is power?
• Rate at which:
– Work is done
– Energy is consumed
– Energy is produced
• Rate  occurs over time
W Fd
P

 Fv
t
t
Power Plant
• A power plant produces 300 mega
joules of energy in 30 seconds. What is
the power output of the plant?
P = provides
W/t
This means that the plant
its customers with
6 J / 30
10 million
joules
energy
every
P=
300 of
x 10
s second
7 W (or
(Enough
100000
standard
light bulbs
Pto
= keep
1 x 10
10 MW)
continuously lit)
Dog Sled
• A team of dogs pulls a sled with an
average force of 3000 newtons across a
distance of 200 meters in 75 seconds.
What is their power output during this
time?
P = Fd / t
P = (3000 N)(200 m) / 75 s
P = 8000 W (or 8 kW)
Elevator Motor
AHow
motor
pulls
8000 newton
elevator
upward
atbe
an
can
the an
demand
for power
from the
motor
average speed of 3.0 meters
per second. What amount
reduced?
of power is used by the motor?
Pull the cars up
P =atFv
a slower speed
P = (8000orN)(3 m/s)
Use lighter
P = 24,000
elevator
W cars.
Horsepower… Do YOU have it?
• 1 horsepower = 745.7 W
• How can we determine whether or not
you are capable of producing 745.7 W
of power?
• How can we find out if you can do 745.7
Joules of work in a second?