Horses have it… Mechanical Power

power: the rate at which… –WORK IS DONE –ENERGY IS PRODUCED OR CONSUMED –unit: WATT Definitions Equation

A power plant produces 300 mega joules of energy in 30 seconds. What is the power output of the plant? This means that the plant provides its customers with 10 million joules of energy every second (Enough to keep standard light bulbs continuously lit) Example #1 – Power Plant P = W / t P = 300 x 10 6 J / 30 s P = 1 x 10 7 W (or 10 MW)

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) Example #2 – Dog Sled

A motor pulls an 8000 newton elevator upward at an average speed of 3.0 meters per second. What amount of power is used by the motor? Pull the cars up at a slower speed or Use lighter elevator cars. P = Fv ̄ P = (8000 N)(3 m/s) P = 24,000 W How can the demand for power from the motor be reduced? Example #3 – Elevator Motor

End of PRACTICE