Power
True or False: Power is a Scalar quantity
True
True or False: Efficiency = Output Energy / Total Input Power
False
State the 2 formulas of Mechanical Power
P=Work/time
P=F*v (Force, Velocity)
True or False: Efficiency in reality is always < 100%
True
A girl (of mass= 45 kg) increases her velocity from 3 m/s to 6 m/s in 3 seconds (same direction). Find the Mechanical Power necessary for this girl to accelerate.
P=202.5 W
A light bulb converts 9% of the electrical energy it receives into light energy. If the bulb receives 150 J of electrical energy, how much light energy does it produce?
13.5 J of light energy
A car moves thanks to a Thrust of 6300 N and covers a displacement s=30 m in 6 seconds. How much is the power output on the car wheels?
P=31500 W (or 31.5 kW)
An Onshore Wind turbine delivers 3 MW of Power. If its efficiency is 54%, how much power does the Turbine have to receive from the Wind?
Power from the wind = 5.56 MW
A 1800 kg car is moving along a straight road. The Thrust is 6300 N and the coefficient of rolling friction (wheel/road) is 0.3, how much is the net Power that makes the car moving forward in the same time? (covered displacement = 45 m, in 6 seconds).
Consider g=9.81 m/s^2
P(net) = 7520 W (7.52 kW)
A Solar Panel receives typically 900 W/m2 of power from the Sun. If a Solar Panel is 3 m2 in size, and its efficiency is 24% (highly efficient to be a solar panel), how much electric power does the panel deliver?
Electrical Power = 648 W