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Power Scenario
Power Scenario
Proper technique, not sure why he is jaundiced.
Within the ACS weight room the arguments continue. Which technique is more useful: explosive power or raw strength? Two Vipers are engaged in a squat competition. While performing a squat lift, Abe can raise 170-kg, 0.95 m in a time of 1.5 s. The 87-kg athlete claims that regardless of the amount of time needed to raise the bar, it is all about the maximum mass you can lift. Sixty-four kilogram Zeb on takes 0.95 s to lift a 110kg squat a distance of 1.15-m.
Determine the work done and power of each athlete.
Match the athlete with the appropriate sport and/or position.
Determine the Horsepower of each athlete. (1 hp = 746 W)
Power as rate of energy transfer
Power as rate of energy transfer
Power P is the rate of doing work. It is measured in Watts (W) – named after the Scottish inventor and engineer James Watt (1736-1819). 63 years after Watt's death, the British Association gave his name to the unit of electrical power - and today James Watt's name is to be found written on almost every light bulb in the world. 1 Watt equals 1 Joule per second. Watt also created the term horsepower (1 hp = 746 W).
Power is the rate of doing Work.
Since:
We can substitute...
Therefore,
Power is also the speed at which a force moves.
What is the difference between a kW and a kWh?
What is the difference between a kW and a kWh?
A kW is a kilowatt, meaning using 1000 J of energy each second.
This is a measurement of POWER.
A kWh is a 1 kilowatt x 1 hour of time.
This is a measurement of ENERGY.
Power companies charge by the kWh. The meter on your house measures the rate at which energy (J) is delivered. There are several types of meters, a common variety has a spinning metal disc that indicates the rate of energy consumption (power), like a speedometer on your car. However, the electric company is worried about the odometer (measure of distance traveled) on your car, which is the amount of energy used.
In the sample bill to the right, the customer used 2176kWh of electricity, and was charged a 'tiered' amount:
0-1600 kWh = $0.10799 / kWh
1600 kWh + = 0.14320 / kWh
Similar to a phone data plan, there is a certain rate for the the first block, then a different pricing plan goes into effect.
How would this knowledge affect your energy usage?
Some Additional Resources
Some Additional Resources
Energy Transfer and Power Problem Solving
Energy Transfer and Power Problem Solving
Please make a copy of the following document: Energy Transfer and Power
Submit a copy of your work on the Google Classroom assignment: Energy Transfer and Power
This also listed on 02.3e - Work Done a System
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