physics

Principle /law of moments

When a system is balanced/in equilibrium, the sum of the clockwise moments is equal to the sum of anticlockwise moments, measured from the same pivot

2 conditions for equilibrium

The sum of the upwards force is equal to the sum of the downwards force

Principle of moments applies

Center of gravity

The point through which is where the whole weight acts for any orientation of the object

When does a body topple

When the vertical line through its cog falls outside its base

What are the states of equilibrium

Stable, unstable, neutral

Moments

The turning effect created when a force acts at a distance away from a pivot.

What is the formula for moments

M = FD

Newtons 3rd law

To every action there is an equal and opposite reaction

Newtons 1st law

If no external force is acting on it, an object will

-if stationary, remain stationary

-if moving, keep moving at a steady pace

Scalar quantities

Those having only size

Eg of scalar quantities

Mass, volume, area

Vector quantity

Having size and direction

Eg of vector quantity

Velocity, weight, force

Thermal energy

The total kinetic energy of an objects atoms and molecules

Temperature

The average KE of the particles in a material, measured in c* or K

Heat

The flow of thermal energy from an object of a particular temp to another object of a lower temp

Expansion

When something gets bigger because it is heated

Radiation

The heat transfer traveling through a vacuum or gas until it is absorbed by another object

Specific heat capacity

The amount of heat energy required to raise the temp of a 1kg body by 1*C

Power

The rate of doing work or the rate of consuming energy

Hooked law

The extension and load are proportional, provided the elastic limit was not exceeded

Elastic

When a shape goes back to its original form

Plastic

When a shape keeps its new form

Work

Is said to be done when a force produces motion

Formula of work

WD = FD

Unit of work

Joules (J)

Energy

The ability to perform work

formula Kinetic energy

Used in question to determine velocity KE = ½ MVto the power of 2

Potential energy formula

PE = mgh mass times gravity times height

The principle of conservation of energy

Energy can be changed from one form to another, but it cannot be created or destroyed

Pressure

The amount of force applied to a known area

Who discovered pressure

Blaise pascal

Pressure units

N/m to the power of 3 also Pa

Pressure formula

P = F/A

Pressure in liquids firmula

P=p(slanted)gh

1kPa = ?

1000Pa

What does pressure increase with

Depth

What is pressure at the bottom of the water surface called?

Atmospheric pressure

Force

A push or pull which one object applies to another

Force units

N newtons with a newton meter

Weight formula

W = mg

G on earth

10

G on moon

1.6

G in space

0

Difference is mass and weight

Mass measured in kg weight measured in n, mass measured w and electronic balance weight measured with a newton meter

Types of pressure

Weight, upthrust/boyancy, air resistance, friction, tension, reaction, drag, thrust

How to reduce friction

By lubricating and polishing surfaces

Mass

The amount of matter in a substance (kg)

Volume

The amount of space taken up (m to the power of 3)

384.4 Mm =?m

384, 400, 000

Density

The amount of mass per unit volume. Measured in g/cm cubed or kg/mcubed

Formula of density

Slanted p = m/v

Density of water

1g/cmcubed or 1000kg/mcubed

When does an object sink density

It sinks in a liquid of a smaller density than its own

Density of solids

Constant

Density of liquids and gases

Vary depending on pressure and temp

Why is oil better in a hydraulic press

Because it stops rust and has low freeze point

Evaporation

When the surface, hotter, more energetic liquid paricles break the bond between them and escape as gas particles

Conduction

A method of heat ransfer which occurs in mainly solids whereby energy is passed on from hotter, more energetic particles to neighboring particles via contacti

Convection

A method of heat transfer which occurs in fluids whereby the hotter, less dense particles rise and the cooler more dense particles sink creating a current

Atmospheric pressure

The force of air pressing down on the Earth and everything on it because of the weight of the air above.

What is used to measure atmospheric pressure

Barometer

Reaction formula

Reaction = m times g