Energy used by a CD player, and height in mgh

In summary, the conversation discusses how to calculate the length of time a portable CD player can operate on the energy required to lift it through a height of 1 m. The solution involves finding the power used by the CD player in one second and using this to calculate the total potential energy. The experts suggest dividing the total energy by the power used per second to determine the length of time the CD player can run on this energy.
  • #1
map7s
146
0

Homework Statement



A portable CD player uses a current of 7.1 mA at a potential difference of 3.5 V. In 65 sec, the CD player uses 1.5925 J of power. Suppose the player has a mass of 0.61 kg. For what length of time could the player operate on the energy required to lift it through a height of 1 m?

Homework Equations



I thought at first of using 1/2 mv^2 +mgy = 1/2 mv^2 +mgy with initial and final values, but then I realized that I would not be able to solve for v. I am not quite sure how to incorporate the information that they give in order to find out the answer.
 
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  • #2
Solve for v? I don't follow you. The easiest way to do it, would be to find the power it uses in one second. Then find the total potential energy for 1m. Do you follow me? btw, power is measured in watts; watts = joules/second.
 
  • #3
Wow...that's so much easier! So I would use U=mgh and then set that equal to how much power the CD player uses (which is given) over seconds and solve for how many seconds it takes? mgh = 1.5925 J/ x sec.
 
  • #4
map7s said:
Wow...that's so much easier! So I would use U=mgh and then set that equal to how much power the CD player uses (which is given) over seconds and solve for how many seconds it takes? mgh = 1.5925 J/ x sec.

Reread what you just wrote. You're saying that mgh = 1.5925 J. We know the total energy used in 65s is 1.5925J. Find how much energy is needed per second. Then find the amount of PE (mgh). This will be the total amount of energy that will be made available to the player. Since you know how much energy is needed per second, you can find how long it will be powered by mgh.
 
  • #5
So...the energy that is needed per second can be calculated by taking the total energy and dividing it by the time that was originially given. and then mgh can be calculated from the information given...but then how do I solve for the energy needed to move the particle to that distance? Do I multiply my two numbers together?
 
  • #6
So...the energy that is needed per second can be calculated by taking the total energy and dividing it by the time that was originially given.
Yup
and then mgh can be calculated from the information given
Its as simple as that.
but then how do I solve for the energy needed to move the particle to that distance? Do I multiply my two numbers together?
Move particle? You lost me with that. I thought we were listening to a CD player.

Knowing the total PE and the energy the CD player uses per second, can't you figure out how long the CD player will run from the calculated PE?
 
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  • #7
Sorry, it is a CD player...I meant that if I wanted to find out how much time it would take for the CD player to run on that energy, would I have to multiply the two numbers together ?
 
  • #8
This is what I wrote:
Knowing the total PE and the energy the CD player uses per second, can't you figure out how long the CD player will run from the calculated PE?
There is no multiplication here. You know the energy it uses per second, and you have the total quantity of energy. Just do the math...
 

FAQ: Energy used by a CD player, and height in mgh

1. How does a CD player use energy?

A CD player uses electrical energy from a power source to power its internal components, such as the motor that spins the disc and the laser that reads the data from the disc. This energy is then converted into sound energy that is emitted through the speakers.

2. What type of energy does a CD player use?

A CD player primarily uses electrical energy, but it also converts this energy into kinetic energy to spin the disc and sound energy to produce music.

3. Does a CD player use more energy if the volume is turned up?

Yes, turning up the volume on a CD player requires more energy as it increases the power needed to produce louder sounds. This means that the CD player will use more electrical energy to amplify the sound.

4. How does height affect potential energy in relation to mgh?

The potential energy of an object increases with its height above the ground, as described by the equation PE = mgh. This means that the higher an object is raised, the more potential energy it has.

5. Can a CD player use gravitational potential energy?

No, a CD player does not use gravitational potential energy as it does not rely on the force of gravity to function. The energy used by a CD player is primarily electrical and mechanical.

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