Physics 1

Density(p) formula

P=m/v (density = mass / volume)

density definition

• mass per unit volume

• (units = kg/mcubed)

how to measure the volume of an irregular solid

use an eureka can and a measuring cylinder. When an object is dropped in the eureka can. its volume in the form of water spills into the measuring cylinder

how to measure density of a liquid

• find volume + mass by placing a measuring cylinder on a balance.

• poor the liquid into the measuring cylinder and measure the volume + mass

• more of the liquid = more accurate results

kinetic energy formula

K.E = ½ mvsquared. half mass x velocity squared

change in gravitational potential energy formula

= mass x gravity x change in height

velocity definition

speed in a given direction

friction definition

the force between two surfaces that may impede relative motion and produce heating

weight(kg) formula

w=mg (weight = mass x gravity)

Gravity on earth

9.8N

mass formula

m=w/g (mass = weight / gravity)

What is a force?

It is a vector quantity. Has direction and magnitude.

How to find net force

Add vectors

Force(N) formula

Same as weight F=mg

Force applied formula

F=ma (force = mass x acceleration)

What is terminal velocity

when a free falling object reaches its maximum speed due to the resistance medium it is passing through not letting it go faster.

The air resistance becomes the same as the weight of the free falling object and therefore the resultant force = 0N

what is an reactive force

• an opposite force

• when an object is resting on a surface force acts at a right angle from surface

state Hooks law

the extension of a spring is directly proportional to the force applied

what is constant proportionality

the constant value of the ratio between proportional quantities

constant proportionality formula

k = y/x (constant proportionality = point on graph(y)/point on graph(x) Newton per meter / meter

constant proportionality = how many newtons it would take to stretch the object by 1m.

force applied to spring formula

F=kx (force = constant proportionality x distance(m))

turning effect formula

T.E=Fxd (turning effect = force x distance from pivot)

when is an object at equilibrium

when there is no resultant force and no resultant moment

center of gravity definition

the location where an object’s weight appears to act

how to find the center of gravity experiment

• suspend an irregularly shape from a clamp stand

• attach a plumb line to the clamp stand

• mark the plumb line on the object using a pencil

• remove the object and suspend from a different point and then repeat steps 2 and 3

• repeat step 4 until at least 4 lines are drawn on the object

• the center of gravity is where the lines meet

acceleration formula

m/s/s (meters per second / second) or change in velocity/change in time.

measured in m/s squared

how to find the gradient on a curved line on a distance time graph

• draw a tangent at that point

• pick two points on that tangent

• use acceleration formula

Preassure formula

Pa =F/A (force / area)

how to find distance travelled on velocity time graph

find area under curve

speed + average speed formula

speed - distance / time

average speed - total distance / total time

Power formula

Watts(W) =Work/time

vector and scalar quantaties

vector- has magnitude + direction (force,weight,velocity,acceleration and gravity)

scalar- has magnitude (distance,speed,time,mass,energy,temperature)

limit of proportionality

the point beyond hooks law is no longer true when stretching a material. Object can no longer go back to original

principle of conservation of energy

energy cannot be created or destroyed. It can be transformed from one to another.

time period formula

1 / frequency T=1/f

mass definition

a measure of the quantity of matter in an object

mechanical work done formula

W=Fd=change inE, force x distance =

efficiency formulas

(useful energy output/total energy input) x 100

(useful pwer output/total power input) x 100

what is the radiation from the sun used for

the main source of energy for all energy resources except geothermal, nuclear and tidal

advantages and disadvantages of geothermal energy

• advantages - does not pollute the environment, building it only disrupts the environment slightly

• disadvantages - expensive, can only be built in certain parts of the world