Instantaneous Power calculation

In summary, the energy of a system increases at a rate of 3.5t + 6.2t^2 in joules. The instantaneous power at t=3.1 seconds can be found by taking the derivative of the work with respect to time and plugging in 3.1 seconds. This gives a power of 1.12 + 4t in watts. To find energy, the power can be summed or integrated over a time period. To find instantaneous power, the time period is decreased to a very small value, resulting in a smaller time interval for the calculation.
  • #1
Le_Anthony
17
1

Homework Statement


The energy of a system increases at a rate of 3.5t + 6.2t^2, in joules.
What is the instantaneous power at t=3.1 s?

Homework Equations


P=dW/dt
J/s=watt

The Attempt at a Solution


dW=3.5 + 12.4t
P=(3.5 + 12.4t joule) / (3.1s)=1.12 + 4t, in watts

Yes/ no?
 
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  • #2
Le_Anthony said:

Homework Statement


The energy of a system increases at a rate of 3.5t + 6.2t^2, in joules.
What is the instantaneous power at t=3.1 s?

Homework Equations


P=dW/dt
J/s=watt

The Attempt at a Solution


dW=3.5 + 12.4t
P=(3.5 + 12.4t joule) / (3.1s)=1.12 + 4t, in watts

Yes/ no?

No.
 
  • #3
dW=3.5 + 12.4t
No, it's dW/dt = 3.5 + 12.4t

Why did you divide by 3.1? What units would your answer have?
 
  • #4
Le_Anthony said:

Homework Statement


The energy of a system increases at a rate of 3.5t + 6.2t^2, in joules.
What is the instantaneous power at t=3.1 s?

Homework Equations


P=dW/dt
J/s=watt

The Attempt at a Solution


dW=3.5 + 12.4t
P=(3.5 + 12.4t joule) / (3.1s)=1.12 + 4t, in watts

Yes/ no?
no, they are asking for the instantaneous power at t=3.1

why would the power at 3.1 secs be dependent on time?

1 watt does equal 1 joule per second.

I'll give you a few hints.
The average power dissipated during a time period is energy/ the time period. What happens when you decrease that time period to a very small value?

another hint. To find energy simply sum (integrate) the power. how do you go the other way?
 
  • #5
donpacino said:
no, they are asking for the instantaneous power at t=3.1

why would the power at 3.1 secs be dependent on time?

1 watt does equal 1 joule per second.

I'll give you a few hints.
The average power dissipated during a time period is energy/ the time period. What happens when you decrease that time period to a very small value?

another hint. To find energy simply sum (integrate) the power. how do you go the other way?

So i just need to derive the equation and plug in 3.1s?
I divided by 3.1 because instantaneous power is derivative of work w/ respect to time.
 
  • #6
Le_Anthony said:
So i just need to derive the equation and plug in 3.1s?
I divided by 3.1 because instantaneous power is derivative of work w/ respect to time.
which i now realize i was thinking of W/Δt.. oops
 

What is instantaneous power calculation?

Instantaneous power calculation is the measurement of the rate at which energy is being transferred or used at a specific moment in time. It is typically represented by the letter P and measured in watts (W).

How is instantaneous power calculated?

Instantaneous power can be calculated by dividing the change in energy by the change in time, or by multiplying the voltage and current at a specific moment in time. It can also be calculated using the formula P = VI, where V represents voltage and I represents current.

What is the difference between average power and instantaneous power?

The main difference between average power and instantaneous power is the time period over which they are measured. Average power is calculated over a longer period of time, while instantaneous power is measured at a specific moment in time. Average power provides an overall picture of energy usage, while instantaneous power shows how energy is being used at a particular moment.

Why is instantaneous power important in scientific research?

Instantaneous power is important in scientific research because it allows for a more detailed and accurate analysis of energy usage and transfer. It can provide insights into the performance and efficiency of systems and can help identify potential issues or improvements. It is also a crucial factor in understanding the behavior and characteristics of different materials and devices.

What are some applications of instantaneous power calculation?

Instantaneous power calculation has many applications in various fields, including engineering, physics, and biology. It is commonly used in the design and analysis of electrical systems, as well as in the study of energy transfer and conversion. It is also used in research on human and animal physiology to measure the energy expended during physical activities.

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