physics 220426

centre of mass

a point on the body at which the mass of the body may be thought to be concentrated

stability depends on…

• width of the base

heights of centre

moment

• turning effect of a force

how to calculate moments

moment (Nm) = force (N) * perpendicular distance to the force (m)

gears

• rotating wheel with teeth

used to transmit/multiply rotational forces

gears (moments and speed)

speed

a gear with double the amount of teeth will turn at half the speed when interacting with another gear ( that has half the number of teeth as the other gear)

moment

the moment of the first gear will be twice as big (since the radius is twice the size)

pressure equation

pressure (N/m^2) = force (N) / area (m^2)

pressure in gases and liquids equation

pressure = phg

p = density of liquid h = height of container g = gravitational field strength

pressure = density of liquid * height of container * gravitational field strength FOR GASES AND LIQUIDS

what happens if you reduce the volume of a gas?

halving the volume doubles the pressure

upthrust

A force that pushes things up in liquids and gases.

DUE TO the larger amount of pressure at the bottom (due to the weight of the top) of an object compared to the top of an object.

DUE TO the larger amount of pressure at the bottom (due to the weight of the top) of an object compared to the top of an object.

how does an object float?

if weight = upthrust

how does an object sink?

if weight > (greater than) upthrust

what is a fluid

a fluid is a liquid or a gas. A fluid flows and can change shape to fill any container

principle of moments

The Principle of Moments states that when a body is in equilibrium, the sum of clockwise turning moments about a pivot is equal to the sum of anticlockwise turning moments about the same pivot.