2.5 Hydraulics

Question 1

What are liquids virtually (adjective) and what does this property mean?

Answer 1

Liquids are virtually incompressible so this means that force exerted on one point of the liquid will be transmitted to other points on the liquid

Question 2

Where is pressure on a liquid transmitted?

Answer 2

Equally in all directions

Question 3

Name two ways to increase pressure

Answer 3

• increase the force applied

* decrease the area it is applied to

Question 4

What is pressure?

Answer 4

Force per unit area

Question 5

Why do tanks have large tracks?

Answer 5

Because it has such a massive weight the area needs to be bigger so the pressure is lower so it doesn’t drive straight into the ground and sink

Question 6

When is pressure higher in a liquid and why?

Answer 6

Pressure in a liquid is higher when it’s deeper because it has more mass above it

Question 7

Describe 2 properties of pressure in liquid

Answer 7

• acts in all directions

* increases with depth

Question 8

What is the use of hydraulic pressure systems in machines?

Answer 8

To make it move

Question 9

How do hydraulic pressure systems work?

Answer 9

Because liquids are incompressible, the force applied to it can be transferred so the force through the water causes things to move on the other side

Question 10

Name 3 things that the force exerted by a hydraulic pressure system relies on

Answer 10

• the force exerted on the system
• the area of the cylinder on which this force acts
• the area of the cylinder that exerts the force

Question 11

What effect does the use of cylinders with different cross sectional areas in a hydraulic pressure system have on the force exerted by the hydraulic pressure system?

Answer 11

The use of cylinders with different cross sectional areas on the effort and load sides of a hydraulic pressure system means that the system can be used as a force multiplier, therefore a small effort can be used to move a large load

Question 12

Why is pressure constant in hydraulic pressure systems?

Answer 12

Liquids are incompressible

Question 13

Describe pressure in a hydraulic pressure system

Answer 13

IT IS CONSTANT!!!

Question 14

What is the relationship between the effort applied to the hydraulic pressure system and the force produced by it?

Answer 14

The effort will always be less than the force produced by it because it acts as a force multiplier so it is more efficient

Question 15

What is the only way to reduce the pressure of an object in contact with the ground if the weight (force) is constant?

Answer 15

Increase the cross sectional area in contact with the ground

Question 16

Describe how a hydraulic pressure system works as a force multiplier

Answer 16

Because the pressure must stay the same in the liquid and the cylinders have different cross sectional areas the force must have to change in order to keep the pressure equal the whole way through.

By increasing the cross sectional area of the cylinders, the force will have to increase massively in order to keep the pressure the same in the liquid.

Question 17

What is the equation for pressure?

Answer 17

P=f/a

Where:
P is pressure in pascals (Pa or N/m2)
F is the force in newtons (N)
A is the cross sectional area at right angles to the directions of the force in metres squared (m2)