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1d
comment When pressure is exerted on parallel hydraulic pistons, do they start extending at the same time?
You don't actually pump more water under the piston, as you say. The usual model is that you instantaneously increase the pressure without any flow. That requires that the fluid be incompressible and the reservoirs be perfectly rigid. Both of these are approximations, but if the pressure source can provide a little flow they may be acceptable. They make calculations much easier. For class problems, they are what you assume unless told differently. In the real world they can be the source of failure.
1d
comment When pressure is exerted on parallel hydraulic pistons, do they start extending at the same time?
You should be assuming that there is enough fluid that can be supplied to maintain the pressure in both cylinders.
1d
comment When pressure is exerted on parallel hydraulic pistons, do they start extending at the same time?
That is a reasonable explanation for one starting before the other, though if it is not specified that the pressure rises in the problem one assumes it is a step function. It still doesn't explain the second cylinder waiting for the first to finish. The second should start to rise as soon as the pressure is high enough. Of course, if the pressure rises slowly enough, the first might be done by the time the second starts.
1d
comment When pressure is exerted on parallel hydraulic pistons, do they start extending at the same time?
Your logic is fine. Each cylinder doesn't know the other is there. It has pressure (assumed fixed, not reduced by flow rate) at its input, mass on top making a downward force, and you do a force balance as you have done. If the force is net upwards it will move. I'll be interested in your tutor's explanation.
1d
answered When pressure is exerted on parallel hydraulic pistons, do they start extending at the same time?
Apr
17
comment Can a force applied to a wheel find the fastest way of getting to the other side?
No, the highest speed of sound in an element I see is carbon at 16200 m/sec, far from $3\cdot 10^8$
Apr
16
answered Can a force applied to a wheel find the fastest way of getting to the other side?
Apr
15
answered water pressure in the oceans or great lakes
Apr
10
comment Kepler's third law doesn't give earth's orbital period! Why?
An error of one part in $10^4$ is quite reasonable when one of the inputs has only three digits of accuracy. That is much larger than the planetary perturbations.
Apr
7
revised How to model a rising helium balloon?
correct english
Apr
2
comment What is the maximum range of a bullet flying through the sky?
The fact that the bullet transitions from supersonic to subsonic makes the air resistance very hard to calculate. It becomes a better candidate for experimentation.
Apr
2
comment What is the maximum range of a bullet flying through the sky?
The reason the websites work in vacuum is because it is easy. Two constants ($g$ and initial velocity) and you are done. Air resistance is hard. You need to specify the bullet carefully, but the drag coefficient varies with velocity.
Apr
2
answered How does one estimate the electrical power of a power plant?
Mar
31
awarded  Nice Answer
Mar
30
answered Why is an electron still an elementary particle after absorbing / emitting a photon?
Mar
30
answered Free fall question: Bill shoots his gun
Mar
29
answered What will happen to water at $0^\circ$ Celsius kept in large evacuated chamber
Mar
28
awarded  Nice Answer
Mar
27
revised Why must the particles of an ideal gas be point-like?
add info
Mar
27
revised Confused with how to approach this pulley problem (solved)
correct answer