Energy/power A levels physics

• yan_plusheartz
In summary, the conversation involves a discussion about a formula for efficiency, specifically p(out) / p(in) x 100 percent = efficiency. The conversation also touches on the topic of power and the formula for power being P = F x v. The speaker is seeking clarification on whether using ##\rho## x Area x v3 is the same as using P = F x v. They also mention not having values for F and v and struggling to get the correct answer. The other speaker then explains that power is energy / time and suggests using the wind energy and known values for area and wind speed to solve the problem. However, the first speaker mentions not having values for mass and time.
yan_plusheartz
Relevant formula
: p(out) / p (in) x 100 percent = efficiency
My question

My approach

But the right answer is 650kW

You use P = F x v but you write ##\rho## x Area x v3. Is that the same ?

Yeah I understand that it is not exactly the same. But my problem is , I don't have the value for F and v . And the only formula I know for power is force x velocity. So I did it by using the values given to derive a unit which is the same as power. But I can't seem to get the right answer. and I'm not sure whether my approach is correct or not. Can you teach me the correct method?

anyhow, thank you for taking your time to try to solve my question:)

Yes I can. You know that power is energy / time ?
How much energy does the wind bring in /time ?

If that case, the wind energy is 1/2 m (10)*2 am I right? Problem is , I don't have the value of mass and time :(

That is correct. And they give you the area and the wind speed.

1. What is energy and how is it related to power in A level physics?

Energy is the ability to do work or cause change. In A level physics, it is measured in joules (J). Power is the rate at which energy is transferred or used, and is measured in watts (W). The relationship between energy and power is that power is the amount of energy transferred per unit of time.

2. What are the different forms of energy studied in A level physics?

There are several forms of energy studied in A level physics, including mechanical energy, electrical energy, thermal energy, chemical energy, and nuclear energy. Each form of energy has its own unique properties and can be converted into other forms of energy.

3. How is energy conserved in A level physics?

The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another. In A level physics, this means that the total amount of energy in a closed system remains constant, and energy can be transferred between different forms, but the total amount remains the same.

4. What is the difference between potential and kinetic energy in A level physics?

Potential energy is the energy that an object has due to its position or state, such as gravitational potential energy or chemical potential energy. Kinetic energy is the energy an object has due to its motion. In A level physics, potential energy can be converted into kinetic energy and vice versa.

5. How is power calculated in A level physics?

Power is calculated by dividing the amount of energy transferred by the time taken for the energy transfer to occur. This can be represented by the equation P = E/t, where P is power in watts, E is energy in joules, and t is time in seconds. In A level physics, it is important to also consider the efficiency of the energy transfer, as not all of the energy may be converted into useful power.

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