Work as the transfer of energy (video) | Khan Academy
Heat Energy -- a form of energy that is transferred by a difference in temperature. What is The unit of power is the Watt = 1 Joule/ 1 second. One common unit. A single watt (W) is equivalent to one joule (J) per second (S), where a joule is a to 1 amp flowing through a circuit with a 1 volt electric potential difference. Good metaphor-making can make geniuses: Energy conservation is like balancing account-books (Joule). Evolution's “struggle for existence” is.
In other words, it takes 1. Another source provides the following source-to-site ratios for the U. Average energy use per person A nonprofit group in Switzerland, the 2,Watt Societyhas calculated that the current level of worldwide energy use amounts to 2, watts per capita.
Understanding Energy Units - GreenBuildingAdvisor
This is the total amount of energy used continuously, on average, by one person, as long as the person is alive. The amount includes energy used for industry, commercial buildings, residential buildings, municipalities, and transportation — everything.
Per capita energy use in the U. The average American uses about 12, watts — six times the world average. Both weightlifters are giving their weights the same amount of gravitational potential energy. They both lift them two meters, and the masses are kilograms each.
Work as the transfer of energy
Plug those into the formula for gravitational potential energy, and you find that the work done by each weightlifter is 1, joules. But the weightlifter on the right is lifting his weight faster. And there should be a way to distinguish between what he's doing and what the other slower weightlifter is doing. We can distinguish their actions in physics by talking about power.
Power (video) | Work and energy | Khan Academy
Power measures the rate at which someone like these weightlifters or something like an automobile engine does work. To be specific, power is defined as the work done divided by the time that it took to do that work.
We already said that both weightlifters are doing 1, joules of work. The weightlifter on the right takes 1 second to lift his weights, and the weightlifter on the left takes 3 seconds to lift his weights.
If we plug those times into the definition of power, we'll find that the power output of the weightlifter on the right during his lift is 1, joules per second. And the power output of the weightlifter on the left during his lift is joules per second.
A joule per second is named a watt, after the Scottish engineer James Watt. And the watt is abbreviated with a capital W.
Difference Between Energy and Power
All right, let's look at another example. Let's say a 1, kilogram car starts from rest and takes 2 seconds to reach a speed of 5 meters per second. We can find the power output by the engine by taking the work done on the car divided by the time it took to do that work.
To find the work done on the car, we just need to figure out how much energy was given to the car. Now imagine that the skateboarder, who's moving with 10 meters per second, gets stopped because he crashes into a stack of bricks.
The stack of bricks does negative work on the skateboarder because it takes away energy from the skateboarder. To find the work done by the stack of bricks, we just need to figure out how much energy it took away from the skateboarder. Since the skateboarder started with 2, joules of kinetic energy and ends with zero joules of kinetic energy, it means that the work done by the bricks on the skateboarder was negative 2, joules.
It's negative because the bricks took away energy from the skateboarder.how to convert joule to watts electriclal formulas and calculations
Let's say we instead lift the bricks, which are kilograms, upwards a distance of four meters. To find the work that we've done on the bricks, we could use Fd cosine theta.
But we don't have to. We could just figure out the amount of energy that we've given to the bricks.