Chapter 3 Flashcards
. What is the moment of a substance and how is it calculated?
. What is the principle of moment?
. Moment is the turning effect of a force, which is calculated as: Force * perpendicular distance from the point.
. Principle of moments is ‘ when an object is in equilibrium, the sum of clockwise moments about any point is equal to the sum of anticlockwise moment.
What is pressure?
The amount of physical force exerted on an area.
What is known as the ‘centre of mass’ ?
. How does it apply to falling or toppling objects?
. How does it apply with area of objects?
It’s the centre point where an object balances.
. When the centre of mass is situated before the edge of base after tilting it, the object will return to it’s original shape, meaning it’s stable. But it’s unstable when its centre of mass passes over the edge of base.
. The objects with wider base and/or lower centre of mass are more stable.
How does length and force affect moment?
The bigger the length of spanner, the easier the turning effect is to make. The higher the force applied, the more turning effect it has, for having more energy.
What is the word for ‘Up to the point where extension and force are directly proportional’ ?
The limit of proportionality, meaning beyond that point, Hooke’s law changes.
. What does the spring constant tell us about?
. What’s its symbol?
. What’s it measured in and how?
. The spring constant tells us about the stiffness of a substance (how hard they can move)
. Symbol K
. Spring constant = Force/Extension, (n/m).
How is pressure measured?
. Two symbols of it?
By dividing the force by the area, and pressure and area are inversely related.
N/m2, or pascals (pa).
How’d you describe atmospheric pressure?
State some rules about it.
What are the instruments measuring it?
Atmospheric pressure is the force exerted on a substance by the air and atmosphere above it, as gravity pulls it down to the earth.
Atm pressure decreases above sea level, meaning the density is HIGHEST at the bottom of sea, and increasing the height decreases the pressure, weight, density…
Instruments measuring atm are barometers, and manometers (difference in pressure).
Most barometers contain mercury liquid within them, as it’s very highly-dense, and any change in pressure would change its height meaning it measured the atm.
Symbol for pressure in liquid, and its rules.
Pressure in liquid = pgh (p: density, g: 10N/kg, h: height).
. Pressure acts in ALL directions, meaning it puts same amount of force in all the zones of an object underwater.
. Pressure increases with depth: the deeper you go into a liquid, the greater the weight of liquid above and the higher the pressure.
. The denser the liquid the higher the pressure at any particular depth.
What’s known as Boyle’s law?
For a fixed mass of gas at a constant temperature, the volume is inversely related to the pressure.
Also P1 * V1 = P2 * V2.
Facts about mercury columns.
At sea level, atmospheric pressure will support a column of mercury 760 mm high.
