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# Questions tagged [power]

The time rate of change of energy

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11 views

### Mechanical power [on hold]

A constant power Plant is applied to a particle of mass m. What is the distance travelled by the particle when it's velocity increases from v1 to v2?
32 views

### Which weight would be necessary to power a computer with this system? [on hold]

Let's say I install such a system: in a corner of my room, that produces energy in a similar way than grandmother clocks, connected to an alternator (or any other system that transforms mechanical ...
18 views

### Physics for resistors in parallel which resisto is the warmest [on hold]

for all resistors in parallel, which of the three became warmest when a voltage is applied? Explain your reasoning. Rhigh 9930 ohms, Rm 501 ohms, and Rlow is 17 ohms
153 views

### Why does incline on treadmill burn calories faster?

So I was at the gym today, running on the treadmill, when the question hit me: If I run with the treadmill on incline, I burn more calories. Since I run at the same speed, kinetic energy is constant, ...
19 views

### What are simple comparisons of energy draws? [closed]

I have recently attended a Bitcoin mining conference. Some of the attendees were specialists in energy with their business being oriented around building data centres or catering to the needs of data ...
35 views

### What happens to the brightness of bulbs if there is a “bridge” with a bulb connecting 2 branches in a parallel circuit? [closed]

The title might be poorly worded but here is a picture: Bulb A & C is the same, bulbs B & D is the same and bulb E is added to the circuit as shown. What would happen to the current flow/...
35 views

### Confusion in usage of formulae for power dissipated in a circuit

When should we use $\frac {V^2}{R}$ and when to use $I^2R$. Because many times they ask about the power without giving details about series and parallel. I am really confused
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### Why can't we use air pressure to recharge an electric cars battery

If we use energy to accelerate a vehicle, a lot of that energy is lost to drag and friction, especially in an electric vehicle. Why can't we harvest some of that energy using an alternator and some ...
8k views

### How power lines use high voltages with a low current?

I've read that power lines use high voltages and low currents to reduce power loss due to resistance. Looking at the formula for power - P = VI So to increase P, you increase V rather than I for ...
80 views

### How to derive $dW = dE$? [closed]

From the definition of power: $$P \ = \ \frac{dW}{dt} \ = \ \frac{dE}{dt}$$ Multiplying both sides by $dt$, we get: $$dW = dE$$ $1.$ What does this imply? $2.$ Are there any other (perhaps more ...
206 views

### Why is my solar panel more efficient as the temperature increases, rather than less efficient?

I have recently performed an experiment in which I placed a solar panel inside a closed box, together with a heater and a lamp (60W). I increased the temperature using a heater from 20ºC to 50ºC. The ...
57 views

### What does this mean? World consume 14 trillion watts of power [closed]

I am not very clear about this statement. Does that mean in every second we are consuming that much energy?
Generally, it's said that for incoherent laser beam combining, the intensity scales with N (where N = # of lasers), whereas the intensity scales with $N^2$ for coherent combining. I_{array,...