explain how you can determine how much power a circuit will generate if you know the voltage and resistance but not the current
1 answer:
The general formula for power dissipation is:
Power = Current x Voltage
However, if you only know the voltage and the resistance, you can calculate the current using Ohm's Law, which is usually given as:
Voltage = Current x Resistance
However, you can rearrange this to give:
Current = Voltage/Resistance
You can then substitute this into the expression for power dissipation to yield an equation that gives an expression for power in terms of only voltage and resistance:
Power =
/ Resistance
Power = Current x Voltage
However, if you only know the voltage and the resistance, you can calculate the current using Ohm's Law, which is usually given as:
Voltage = Current x Resistance
However, you can rearrange this to give:
Current = Voltage/Resistance
You can then substitute this into the expression for power dissipation to yield an equation that gives an expression for power in terms of only voltage and resistance:
Power =
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Answer:
20 J
Explanation:
Kinetic energy is given as half of the product of mass and the square of velocity of an object:
KE =
where m = mass = 40 kg
v = velocity = 1 m/s
Hence, Mary's kinetic energy is:
KE =
KE = 20 * 1 = 20 J
She has a kinetic energy of 20 J.
Ok i apologise for the messy working but I'll try and explain my attempt at logic
Also note i ignore any air resistance for this.
First i wrote the two equations I'd most likely need for this situation, the kinetic energy equation and the potential energy equation.
Because the energy right at the top of the swing motion is equal to the energy right in the "bottom" of the swing's motion (due to conservation of energy), i made the kinetic energy equal to the potential energy as indicated by Ek = Ep.
I also noted the "initial" and "final" height of the swing with hi and hf respectively.
So initially looking at this i thought, what the heck, there's no mass. Then i figured that using the conservation of energy law i could take the mass value from the Ek equation and use it in the Ep equation. So what i did was take the Ek equation and rearranged it for m as you can hopefully see. Then i substituted the rearranged Ek equation into the Ep equation.
So then the equation reads something like Ep = (rearranged Ek equation for m) × g (which is -9.81) × change in height (hf - hi).
Then i simplify the equation a little. When i multiply both sides by v^2 i can clearly see that there is one E on each side (at that stage i don't need to clarify which type of energy it is because Ek = Ep so they're just the same anyway). So i just canceled them out and square rooted both sides.
The answer i got was that the max velocity would be 4.85m/s 3sf, assuming no losses (eg energy lost to friction).
I do hope I'm right and i suppose it's better than a blank piece of paper good luck my dude xx
