Igcse Physics

Front 1

1.1: Length and Time

Back 1

Ruler: Used to measure lengths for distances between 1mm and 1m.

To find the volume of a regular object, you can use a mathematical

formula, you just need to make a couple of length measurements.

Front 2

Measuring cylinders

Back 2

To measure the volume of an

irregular object, you have to put the object into measuring cylinder with water.

When you add the object, it

displaces the water, making the

water level rise. Measure this rise to give the volume of the object.

Front 3

Micrometers

Back 3

Front 4

Time

Back 4

An interval of time is measured using clocks.

To find the amount of time it takes a pendulum to make a spin, time ~25 circles and then divide by same number as the number of circles.

Front 5

1.2: Motion

Back 5

Average speed equation:

total distance/total time

Acceleration:

change in velocity/time taken

Front 6

Definitions

Back 6

Speed: Distance travelled per unit time.

Velocity: The rate of increase of distance travelled in a specified

direction with time.

Front 7

Speed/Time Graph

Back 7

A straight horizontal line means that speed is constant.

If the line is increasing, the moving object is accelerating.

If the line is decreasing, it means the moving object is decelerating.

Front 8

Distance/Time Graph

Back 8

Time is increasing to the right, but its distance does not change, so it is at rest.

The time and distance is

increasing constantly, so it moves at a constant speed.

Front 9

Summary

Back 9

Front 10

Acceleration

Back 10

An increase in speed is a positive acceleration.

A decrease in speed is a negative acceleration/ deceleration.

If the acceleration isn't constant, the line on the graph will be curved.

Front 11

Acceleration and Gravity

Back 11

The downward acceleration of an object is caused by gravity.

This happens most when an object is in free fall.

Objects are slowed down by air resistance.

Once the air resistance is equal to the force of gravity, the object has reached terminal velocity. This means that it will stay at a

constant velocity.

Front 12

Gravity

Back 12

The value of gravity on Earth is 9.81m/s2. However, 10m/s2 is used in most calculations.

Gravity= 2 x height dropped/ (time)2

g=2h/t2

This only works when there is no air resistance, so a vacuum chamber is required.

Front 13

1.3: Mass and Weight

Back 13

Mass: The property of an object that is a measure of its resistance to

accelerate, the amount of matter it contains and its influence in a

gravitational field.

Weight: It is the force of gravity acting on an object, measured in

Newtons, and given by this formula:

Weight= mass x acceleration due to gravity.

Weights may be compared using a balance.

Front 14

1.4: Density

Back 14

To determine the density of a liquid place a measuring cylinder with some liquid. The change in mass is the mass of the liquid and the volume is shown on the sale, then use this formula:

Density= mass/volume

To determine the density of an object, you use the methods used in 1.1 to find the volume and then weigh the object and use the formula.

Front 15

1.5: Forces

(i) Effects of forces

Back 15

A force may produce a change in size and shape of a body, give the

acceleration or deceleration or a change in direction depending on the direction of the force.

Front 16

Extension/Load Graph

Back 16

Front 17

Experiment

Back 17

Finding the resultant force of two or more forces acting along the same line:

Front 18

Experiment Continued

Back 18

Front 19

Hooke's Law

Back 19

Hooke's law: Springs extend in proportion to load, as long as they are under their proportional limit.

Equation:

Load (N) = spring constant (N/mm) x extension (mm)

F=kx

Front 20

Definitions

Back 20

Limit of proportionality: Point at which load and extension are no longer proportional.

Elastic limit: Point at which the spring will not return to its original shape after being stretched.

Force = mass x acceleration

Front 21

Newtons

Back 21

Forces are measured in Newtons.

1 Newton is the amount of force needed to give 1kg an acceleration of 1m/s2 (if you think about it using the equation it's really obvious: if force = mass x acceleration, then 1 Newton = 1kg x 1m/s2)

Front 22

Circular Motions

Back 22

An object at a steady speed in a

circular orbit is always

accelerating as its direction is changing, but it gets no closer to the centre.

Front 23

Centripetal force

Back 23

This is the force acting towards the centre of a circle.

It is a force that is needed (not caused by) a circular motion, e.g.: when you swing a ball on a string round a circle, the tension of the string is the centripetal force. If the string is cut, then the ball will travel in a straight line at a tangent to the circle at the point where the string was cut

(Newton's first law).

Front 24

Centrifugal force

Back 24

This is also know as the non-existent force is the force acting away the centre of a circle.

This is what makes a slingshot go outwards as you spin it. The

centrifugal force is the reaction to the centrifugal force (Newton's third law).

It has the same magnitude, but opposite direction to the centrifugal force ("equal but opposite").

centripetal force = mass x velocity2 / radius.