# Power spent to keep a spring compressed

• MatheusMazur
In summary, the conversation discusses the calculation of power necessary to keep a spring compressed using an engine or solenoid. It is determined that the work required is dependent on the force needed to compress the spring, and the power input can be found in the data sheet for the solenoid. It is also mentioned that in order to hold the motor in place without consuming power, it would need to have ideal components such as superconducting windings.
MatheusMazur
I was wondering, I have an engine that should keep a spring compressed. How can I calculate the power necessary for this?
The work is Force x Distance, as there is no distance, there is no work, so no power... But obviously to keep the spring compressed the engine will have to produce a constant force and spend energy... So what am I missing?

You are not missing anything.
If you turn the motor off and lock it into place, it will hold the spring and not consume any power.

MatheusMazur and Wrichik Basu
But, for example, if the spring is kept compressed by a coil, electricity must be flowing through the coil to keep the pressure, won't it require electrical power to keep producing this constant force?

MatheusMazur said:
But, for example, if the spring is kept compressed by a coil, electricity must be flowing through the coil to keep the pressure, won't it require electrical power to keep producing this constant force?
That's just an inefficient was of holding the motor in place. The motor will not move, and the power will go into heating up the motor. If the motor was using superconducting windings and other ideal components, it would hold so long as the power input was kept open (disconnected).

russ_watters and MatheusMazur
MatheusMazur said:
Got it. This question came to me after observing a spring return solenoid valve. It works with 24V and I wondered how could I calculate the necessary current to keep the spring compressed... Is there a way to calculate it?
It is extremely difficult to calculate. Much simpler to look up the data sheet for the solenoid. The data sheet should say how much power is needed to keep it energized.

russ_watters and MatheusMazur
anorlunda said:
It is extremely difficult to calculate. Much simpler to look up the data sheet for the solenoid. The data sheet should say how much power is needed to keep it energized.

Thanks!

Electrical power going into solenoid is dependent upon force that it is required to push.
This is then dependent upon the spring's rate constant multiplied by compression amount (displacement) needed.

This is similar to how peak-n-hold fuel-injectors work. A larger burst of power is needed to initiate the opening of the injector and open the solenoid fully against spring. Then power is backed down to just enough to keep it in that position for duration of injector pulse.

## What is the definition of "power spent to keep a spring compressed"?

The power spent to keep a spring compressed is the amount of energy required to maintain the spring in a compressed state. This energy is typically measured in joules.

## How is the power spent to keep a spring compressed calculated?

The power spent to keep a spring compressed can be calculated using the formula P = Fv, where P is power, F is force, and v is velocity. It can also be calculated using the formula P = kx^2/t, where k is the spring constant, x is the distance the spring is compressed, and t is the time it takes to compress the spring.

## What factors affect the power spent to keep a spring compressed?

The power spent to keep a spring compressed is affected by the spring constant, the distance the spring is compressed, and the time it takes to compress the spring. It can also be affected by external factors such as friction and air resistance.

## How is the power spent to keep a spring compressed used in real-life applications?

The power spent to keep a spring compressed is used in various real-life applications, such as in shock absorbers for vehicles, door closers, and mechanical toys. It is also used in industrial settings for tasks such as stamping and pressing.

## What happens to the power spent to keep a spring compressed when the spring is released?

When the spring is released, the power spent to keep it compressed is converted back into potential energy stored in the spring. This potential energy is then released as kinetic energy as the spring returns to its original state.

Replies
4
Views
1K
Replies
17
Views
1K
Replies
14
Views
1K
Replies
50
Views
10K
Replies
6
Views
1K
Replies
4
Views
667
Replies
10
Views
2K
Replies
9
Views
2K
Replies
4
Views
2K
Replies
8
Views
639