Net force acting on a piston shaft of an actuator

AI Thread Summary
To calculate the speed at which a piston shaft will eject from an actuator, the net force acting on it must be determined. The net force is calculated by subtracting the weight of the piston and the frictional force from the upward force exerted by compressed air. The coefficient of friction is noted, but without knowing the normal force, it complicates the calculation of the frictional force. The length of the actuator is specified as 10 inches, but additional information is needed to proceed accurately. Direct measurement of the frictional force is suggested as a practical approach to resolve uncertainties.
rajdeep1
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Homework Statement


A cylindrical piston shaft weighs 250 g and is held vertically inside an actuator (We can assume actuator is a box with hollow cylindrical space to fit the piston shaft). Compressed air at 100 psi is supplied at the bottom of the actuator and is acting on the piston upwards with a force of 90 N. The coefficient of friction between the piston shaft and the inside wall of the actuator is 0.61. I need to calculate the speed by which the shaft will eject and shoot upwards from the actuator.

Homework Equations


Net Force= ma
d= ui*t+ 0.5*a*t^2

The Attempt at a Solution


Net Force= 90N- 0.25*9.81 - Ff (I am not sure if this is the right way to calculate the net force. Also, not sure how to calculate the frictional force here, although I do know Ff= coeff* R)

Assuming I have a net force, I can easily find the acceleration and the distance it travels in a second.

Thank you so much.
 
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Is this a textbook question or a lab? There is not enough information. You will certainly need to know the length of the actuator.
The coefficient of friction doesn't help with no way to determine the normal force.
 
It is not a textbook question, it is more of a lab question. The length of the actuator is 10 inch.
Is there any other information that we need?
Thank you.
 
rajdeep1 said:
It is not a textbook question, it is more of a lab question. The length of the actuator is 10 inch.
Is there any other information that we need?
Thank you.
As I wrote, the coefficient of friction is no help since there is no obvious way to find the normal force between piston and cylinder. It would be more helpful simply to measure the frictional force.
 
haruspex said:
As I wrote, the coefficient of friction is no help since there is no obvious way to find the normal force between piston and cylinder. It would be more helpful simply to measure the frictional force.
Thank you. Could you please tell me the ways to measure the frictional force then?
 
rajdeep1 said:
Thank you. Could you please tell me the ways to measure the frictional force then?
By direct experiment.
 

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