# Pressure - hydraulic jack

Watch
Announcements
#1
Pascals law states that pressure will be spread un-diminshed throughout a fluid.
This principle can be used to transmit a small force to a large area.
I was watching a lecture explaining that IF THERE WAS NO GRAVITY the pressure transmitted between the two pistons would be the same
BUT
If we account for gravity will this only work if the fluids are on the same level
SO if the piston we push is LOWER than the piston we wish to raise then pressure on the receiving side would be LOWER?

Is this correct?
Thank you
0
7 years ago
#2
(Original post by jsmith6131)
.......If we account for gravity will this only work if the fluids are on the same level?
To a point, but be very careful with the explanation:

You need to separate the pressure due to gravity in the columns of the pistons from the pressure due to the external force applied to the pistons.

Due to the gravity component, the pressure in the two columns of liquid will be the same at equal heights in both columns.

i.e. When one column is a different height, the pressure in both columns due to gravity only (with no other forces acting)will be the same up to the point where both columns are the same height. After that, the pressure due to gravity in the higher column decreases uniformly until zero at full height.

But the pressure component due to the applied external force remains undiminished at all heights.

(Original post by jsmith6131)
SO if the piston we push is LOWER than the piston we wish to raise then pressure on the receiving side would be LOWER?
Only as far as the pressure due to the effect of gravity is concerned. See above explanation.

The pressure due to the force applied to the driving piston remains undiminshed throughout the liquid, including the higher receiving piston.
1
X

new posts
Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### Poll

Join the discussion

#### Poll: What factors affect your mental health most right now? Post-lockdown edition

5.81%
Uncertainty around my education (77)
11.77%
Uncertainty around my future career prospects (72)
11.01%
Lack of purpose or motivation (83)
12.69%
Lack of support system (eg. teachers, counsellors, delays in care) (37)
5.66%
Impact lockdown had on physical health (37)
5.66%
Social worries (incl. loneliness/making friends) (70)
10.7%
Financial worries (41)
6.27%
Concern about myself or my loves ones getting/having been ill (26)
3.98%
Exposure to negative news/social media (39)
5.96%
Difficulty accessing real life entertainment (19)
2.91%
Lack of confidence in making big life decisions (63)
9.63%
Worry about missed opportunities during the pandemic (52)
7.95%