Physical QuantitiesCard 1: What are physical quantities?

Physical Quantities1. A physical quantity is a quantity that can be measured.

2. A physical quantity can be divided into base quantity and derived quantity.

Card 2: What are base quantities?

Base Quantities

Base quantities are quantities that cannot be defined in term of other physical

quantities.

TopCard 3: State the 5 base quantities and their SI unit

5 Base Quantites

Quantity Name of Unit Symbol of Unit

Length metre m

Time second s

Temperature Kelvin K

Mass kilogram kg

Current Ampere A

Card 4: What is derived quantities?

Derived Quantities

A derived quantity is a Physics quantity that is not a base quantity. It is the quantities

which derived from the base quantities through multiplying and/or dividing them.

TopCard 5: What is derived unit?

Derived Unit

The derived unit is a combination of base units through multiplying and/or dividing

them.

Card 6: What are prefixes?

Prefixes

Prefixes are the preceding factor used to represent very small and very large physical quantities in

SI units.

Prefixes Symbol Value

Tera T 1012

Giga G 109

Mega M 106

kilo k 103

desi d 10-1

centi c 10-2

mili m 10-3

micro µ 10-6

nano n 10-9

pico p 10-12

fento f 10-15

TopCard 7: What are scalar quantities?

Scalar Quantities1. Scalars are quantities which are fully described by a magnitude alone.

2. Examples of scalar quantities are distance, speed, mass, volume,

temperature, density and energy.

Card 8: What are vector quantities?

Vector Quantities1. Vectors are quantities which are fully described by both a magnitude and a

direction.

2. Examples of vector quantities are displacement, velocity, acceleration, force,

momentum, and magnetic field.

Error analysisCard 1: What is error?

Error

Error is the difference between the actual value of a quantity and the value obtained

in measurement.

TopCard 2: What is systematic error?

Systematic Error

Systematic errors are errors which tend to shift all measurements in a systematic

way so their mean value is displaced. Systematic errors can be compensated if the

errors are known.

TopCard 3: State 3 sources of systematic error.

Sources of Systematic Error1. zero error, which cause by an incorrect position of the zero point,

2. an incorrect calibration of the measuring instrument.

3. consistently improper use of equipment.

TopCard 4: State 2 precaution steps to reduce systematic error.

Steps to reduce Systematic Error1. Conducting the experiment with care.

2. Repeating the experiment by using different instruments.

TopCard 5: What is meant by zero error?

Zero Error1. A zero error arises when the measuring instrument does not start from

exactly zero.

2. Zero errors are consistently present in every reading of a measurement.

3. The zero error can be positive or negative.

TopCard 6: Define random Error

Random Error1. Random errors arise from unknown and unpredictable variations in

condition.

2. It changes from one measurement to the next.

TopCard 7: State the causes of random error

Causes of Random Error

Random errors are caused by factors that are beyond the control of the observers.

Random error can cause by:

1. personal errors such as human limitations of sight and touch.

2. lack of sensitivity of the instrument: the instrument fail to respond to the

small change.

3. natural errors such as changes in temperature or wind, while the experiment

is in progress.

4. wrong technique of measurement.

TopCard 8: How random error can be avoided or reduced?

How to avoid random error1. Taking repeat readings

2. Find the average value of the reading.

TopCard 9: What is parallax error?

Parallax Error

A parallax error is an error in reading an instrument due to the eye of the observer

and pointer are not in a line perpendicular to the plane of the scale.

Card 1: What is meant by precision?

Precision

Precision is the ability of an instrument in measuring a quantity in a consistent

manner with only a small relative deviation between readings.

TopCard 2: How to measure the precision of a measurement?

Relative Deviation

The precision of a reading can be indicated by its relative deviation.

The relative deviation is the percentage of mean deviation for a set of

measurements and it is defined by the following formula:

TopCard 3: Define accuracy.

Accuracy

The accuracy of a measurement is the approximation of the measurement to the

actual value for a certain quantity of Physics.

TopCard 4: How the accuracy of a measurement can be increased?

How to Increase Accuracy1. taking a number of repeat readings to calculate the mean value of the

reading.

2. avoiding the end errors or zero errors.

3. taking into account the zero and parallax errors.

4. using more sensitive equipment such as a vernier caliper to replace a ruler.

Card 5: What is meant by sensitivity of a measuring instrument?

Sensitivity1. The sensitivity of an instrument is its ability to detect small changes in the

quantity that is being measured.

2. Thus, a sensitive instrument can quickly detect a small change in

measurement.

3. Measuring instruments that have smaller scale parts are more sensitive.

4. Sensitive instruments need not necessarily be accurate.

Card 6: Describe how a micrometer is used to make a measurement.

Micrometer Screw Gauge1. Turn the thimble until the object is gripped gently between the anvil and

spindle.

2. Turn the ratchet knob until a "click" sound is heard. This is to prevent

exerting too much pressure on the object measured.

3. Take the reading.

Reading of main scale = 5.5mm

Reading of thimble scale = 0.27mm

Actual Reading = 5.5mm + 0.27mm = 5.77mm

Scientific InvestigationCard 1: Scientific Report

Scientific Report

A report of the investigation must include:

1. Objective of the experiment,

2. Inference,

3. Hypothesis,

4. Three types of variables: manipulated variable, responding variable and

fixed variable,

5. Defined operational variables,

6. List of apparatus,

7. Procedure,

8. Tabulation of data,

9. Analysis of data,

10. Conclusion.

TopCard 2: What is meant by inference?

Inference

Inference is a statement to state the relationship between two visible quantities

observed in a diagram or picture.

TopCard 3: What is meant by hypothesis?

Hypothesis

Hypothesis is a statement to state the relationship between two measurable

variables that can be investigated in a lab.

TopCard 4: State the 3 variables that need to be control in a scientific investigation?

Variables

A variable is a quantity that can vary in value. There are 3 types of variable:

1. Manipulated Variables: Manipulated variables are factors which changed for

the experiment.

2. Responding Variables: Responding variables are factors which depend on

the manipulated variables.

3. Constant Variables: Constant variables are factors which are kept the same

throughout the experiment.

TopCard 5: Tabulating Data

Tabulating Data

A proper way of tabulating data should include the following:

1. The name or the symbols of the variables must be labelled with respective

units.

2. All measurements must be consistent with the sensitivity of the instruments

used.

3. All the values must be consistent to the same number of decimal places.

Card 6: Drawing graph.

Drawing Graph

Graphs are used to make a relationship between variables. Gradient value and

extrapolation of a graph are used to analyse a graph.

A well-plotted must contain the following features:

1. A title to show the two variables under investigation,

2. two axes labelled with the correct variables and their respective units,

3. the graph drawn is greater than 50 % of the graph paper,

4. appropriate scales (1:1 x 10x, 1:2 x 10x and 1:5 x 10x)

5. all the points are correctly plotted,

6. a best fit line is drawn

Top

2 Force and MotionLinear MotionCard 1: Linear Motion

Linear Motion

Linear motion is the movement of an object along a straight line.

Card 2: What is distance?

Distance

The distance traveled by an object is the total length that is traveled by that object.

Unit: metre (m)

Type of Quantity: Scalar quantity

Card 3: What is Displacement?

Displacement

Displacement of an object from a point of reference, O is the shortest distance of

the object from point O in a specific direction.

Unit: metre (m)

Type of Quantity: Vector quantity

Previous | Top | NextCard 4: What is the difference between distance and displacement?

Distance vs Displacement

Distance travelled = 200m

Displacement = 120 m, in the direction of Northeast

Distance is a scalar quantity,

Displacement is a vector quantity

Previous | Top | NextCard 5: What is speed

Speed

Speed is the rate of change in distance.

Formula:

Unit: ms-1

Type of quantity: Scalar quantity

Previous | Top | NextCard 6: What is velocity

Velocity

Velocity is the rate of change in displacement.

Formula:

Unit: ms-1

Type of quantity: Vector quantity

Previous | Top | NextCard 7: What is acceleration?

Acceleration

Acceleration is the rate of velocity change.Acceleration is a vector quantity

Formula:

Unit: ms-2

Type of quantity: Vector quantity

Previous | Top | NextCard 8: Notes - Acceleration

Notes - Acceleration An object moves with a constant velocity if themagnitude and direction of

the motion is always constant.

An object experiences changes in velocity if

o the magnitude of velocity changes

o the direction of the motion changes.

An object that experiences changes in velocityis said to have acceleration.

An object traveling with a constant acceleration,a, if the velocity changes at a

constant rate.

Previous | Top | NextCard 9: 4 Equations for Uniform Acceleration Motion

4 Equations of Uniform Acceleration

The above equation is for solving numerical problems involving uniform

acceleration.

Previous | Top | NextCard 10: Summary of the equation

Summary

Previous | Top

Ticker TapeCard 1: Ticker Timer

Ticker Timer

A ticker-timer consists of an electrical vibrator which vibrates 50 times per

second.

This enables it to make 50 dots per second on a ticker-tape being pulled

through it.

The time interval between two adjacent dots on the ticker-tape is called one

tick.

One tick is equal to  1/50 s or 0.02 s.

Top | NextCard 2: Analysing Ticker Tape 1 - Uniform Velocity

Uniform Velocity

The distance of the dots is equally distributed.

All lengths of tape in the chart are of equal length.

The object is moving at a uniform velocity.

Previous | Top | NextCard 3: Analysing Ticker Tape 1 - Uniform Acceleration

Uniform Acceleration

The distance between the dots increases uniformly.

The length of the strips of tape in the chart increase uniformly.

The velocity of the object is increasing uniformly, i.e. the object is moving at a

constant acceleration.

Previous | Top | NextCard 4: Analysing Ticker Tape 1 - Uniform Deceleration

Uniform Deceleration

The distance between the dots decreases uniformly.

The length of the strips of tape in the chart decreases uniformly.

The velocity of the object is decreasing uniformly, i.e. the object is

decelerating uniformly.

Previous | Top | NextCard 5: Finding velocity from ticker tape

Finding Velocity

Velocity of a motion can be determined by using ticker tape through the following

equation:

Caution!: 

t is time taken from the first dot to the last dot of the distance measured.

Previous | Top | NextExample 1

Diagram 2.4 shows a strip of ticker tape that was pulled through a ticker tape timer that vibrated at 50 times a second. What is the

a. time taken from the first dot to the last dot?b. average velocity of the object that is represented by the ticker tape?

Answer:

a. There are 15 ticks from the first dot to the last dot, hence

Time taken = 15 × 0.02s = 0.3s

b.Distance travelled = 15cm

$\begin{gathered} v = \frac{s}{t} \hfill \\ v = \frac{{15cm}}{{0.3s}} = 50cms^{ - 1} \hfill \\ \end{gathered} $ Card 6: Findng acceleration

Finding Acceleration

Acceleration of a motion can be determined by using ticker tape through the

following equation:

Caution!: 

t is time taken from the initial velocity to the final velocity.

Previous | Top | NextExample 2

The ticker-tape in figure above was produced by a toy car moving down a tilted runway. If the ticker-tape timer produced 50 dots per second, find the acceleration of the toy car.

Answer:

In order to find the acceleration, we need to determine the initial velocity, the final velocity and the time taken for the velocity change.

Initial velocity,

u = \frac{s}{t} = \frac{{3cm}}{{0.02s}} = 150cms^{ - 1} v = \frac{s}{t} = \frac{{0.5cm}}{{0.02s}} = 25cms^{ - 1}

Time taken for the velocity change,t = (0.5 + 4 + 0.5) ticks = 5 tickst = 5 × 0.02s = 0.1s

Acceleration,

a = \frac{{v - u}} {t} = \frac{{25 - 150}} {{0.1}} = - 1250cms^{ - 1}Example 3

A trolley is pushed up a slope. Diagram above shows ticker tape chart that show the movement of the trolley. Every section of the tape contains 5 ticks. If the ticker-tape timer produced 50 dots per second, determine the acceleration of the trolley.

Answer:

In order to find the acceleration, we need to determine the initial velocity, the final velocity and the time taken for the velocity change.

Initial velocity,

u = \frac{s}{t} = \frac{{5cm}}{{5 × 0.02s}} = 50cms^{ - 1} v = \frac{s}{t} = \frac{{1cm}}{{5 × 0.02s}} = 10cms^{ - 1}

Time taken for the velocity change,t = (2.5 + 5 + 5 + 5 + 2.5) ticks = 40 tickst = 40 × 0.02s = 0.8s

Acceleration,

a = \frac{{v - u}}

{t} = \frac{{10 - 50}} {{0.8}} = - 50cms^{ - 1}

Graph of Motion

Card 1: Displacement - Time Graph

Displacement - Time Graph

In a Displacement-Time Graph, the gradient of the graph is equal to the velocity of

motion.

Top | Next

Card 2: Analysign Displacement - Time Graph

Analysing Displacement - Time Graph

Gradient = 0Hence, velocity = 0

Gradient is constant,hence, velocity is Uniform

Gradient is negative and constant, hence velocity is uniform and in opposite direction

Gradient is increasing, hence velocity is increasing.

 

Gradient is decreasing, hence velocity is decreasing.

 

Previous | Top | Next

Card 3: Velocity - Time Graph

Velocity - Time Graph

The gradient of the velocity-time gradient gives a value of the changing rate

in velocity, which is theacceleration of the object.

The area below the velocity-time graph gives a value of the

object's displacement.

 

Previous | Top | Next

Card 4: Analysing Velocity - Time graph

Analysing Velocity - Time Graph

Uniform velocity Uniform acceleration

Uniform deceleration Increasing acceleration

 

Increasing deceleration  

Previous | Top | Next

Card 5: Converting a Velocity-Time graph to Acceleration-Time graph

Converting a Velocity-Time graph to Acceleration-Time graph

In order to convert a velocity-time graph to acceleration time graph, we need to find

the gradient of the velocity time graph and plot it in the acceleration-time graph.

Previous | Top | Next

Card 6: Graph of free falling 1-Dropping an object from high place

Dropping an object from high place

Velocity - Time Graph Acceleration - Time Graph

Previous | Top | Next

Card 7: Graph of free falling 2 - Launching obejct upward

Launching Object Upward

Velocity-Time Graph Acceleration-Time Graph

Previous | Top | Next

Card 8: Graph of free falling 3 - Object moving upward and fall back to the ground

Object moving upward and fall back to the ground

Velocity-Time Graph Acceleration-Time Graph

Previous | Top | Next

Card 9: Graph of free falling 4 - Object falling and bounces back

Object falling and bounces back

Velocity-Time Graph Acceleration-Time Graph

Mass and Inertia

Card 1: What is mass?

Mass

Mass is the amount of matter.

Unit: kilogram (kg)

Type of quantity: Scalar quantity

Top | NextCard 2: What is inertia?

Inertia

Inertia is the property of a body that tends to maintain its state of motion.

Previous | Top | NextCard 3: State Newton's First Law

Newton's First Law

In the absence of external forces, an object at rest remains at rest and an object

in motioncontinues in motion with a constant velocity(that is, with a constant

speed in a straight line).

Previous | Top | NextCard 4: Situation Involving Inertia 1 - Jerking a Card

Jerking a Card

When the cardboard is jerked quickly, the coin will fall into the glass.

Explanation:

The inertia of the coin resists the change of its initial state, which is stationary.

As a result, the coin does not move with the cardboard and falls into the glass

because of gravity.

Previous | Top | NextCard 5: Situation Involving Inertia 2 - Pulling a Book

Pulling a Book

When the book is pulled out, the books on top will fall downwards.

Explanation:

Inertia tries to oppose the change to the stationary situation, that is, when the book

is pulled out, the books on top do not follow suit.

Previous | Top | NextCard 6: Situation Involving Inertia 3 - Pulling a Thread

Pulling a Thread

Pull slowly - Thread A will snap.

Explanation: 

Tension of thread A is higher than string B.

Tension at A = Weight of the load + Pulling Force

Yank quickly - Thread B will snap.

Explanation:

The inertia of the load prevents the force from being transmitted to thread A,

hence causing thread B to snap.

Previous | Top | NextCard 7: Relation ship between mass and inertia

Larger Mass - Greater Inertia

Bucket filled with sand is more difficult to be moved. It's also more difficult to be

stoppedfrom swinging.

Explanation:

Object with more mass offers a greater resistance to change from its state of

motion.

Object with larger mass has larger inertia to resist the attempt to change the

state of motion.

Previous | Top | NextCard 8: Empty Cart is easier to be moved

Empty cart is easier to be moved

An empty cart is easier to be moved compare with a cart full with load. This is

because a cart withlarger mass has larger inertia to resist the attempt to change

the state of motion.

Previous | Top | Next

Momentum

Card 1:What is momentum?

Momentum

Momentum is defined as the product of mass and velocity.

Formula:

Unit: kgms-1

Type of quantity: Vector

Top | NextExample 1

A student releases a ball with mass of 2 kg from a height of 5 m from the ground. What would

be the momentum of the ball just before it hits the ground?

Answer:

In order to find the momentum, we need to know the mass and the velocity of the ball right

before it hits the ground. 

It's given that the mass, m = 2kg.

The velocity is not given directly. However, we can determine the velocity, v, by using the

linear equation of uniform acceleration.

This is a free falling motion,

The initial velocity, u = 0

The acceleration, a = gravirational acceleration, g = 10ms-2

The dispacement, s = high = 50m.

The final velocity = ?

From the equation

v2 = u2 + 2as

v2 = (0)2 + 2(10)(5)

v = 10ms-1

The momentum,

p = mv =(2)(10) = 20 kgms-1

 

Card 2: Principle of Conservation of Momentum

Principle of Conservation of Momentum

The principle of conservation of momentum states that in a system make out of

objects that react (collide or explode), the total momentum is constant if no

external force is acted upon the system.

Sum of Momentum Before Reaction

= Sum of Momentum After Reaction

Previous | Top | NextCard 3: Formula of Principle of Conservation of Momentum

Formula

Previous | Top | NextExample 2:   Both objects are in same direction before collision.

A Car A of mass 600 kg moving at 40 ms-1 collides with a car B of mass 800 kg moving at 20 ms-

1 in the same direction. If car B moves forwards at 30 ms-1 by the impact, what is the velocity, v,

of the car A immediately after the crash?

Answer:

m1 = 600kg

m2 = 800kg

u1 = 40 ms-1 

u2 = 20 ms-1 

v1 = ?

v2 = 30 ms-1

According to the principle of conservation of momentum,

m1u1 + m2u2 = m1v1 + m2v2

(600)(40) + (800)(20) = (600)v1 + (800)(30)

40000 = 600v1 + 24000

600v1 = 16000

v1 = 26.67 ms-1

Example 3:   Both objects are in opposite direction before collision.

A 0.50kg ball traveling at 6.0 ms-1 collides head-on with a 1.0 kg ball moving in the opposite

direction at a speed of 12.0 ms-1. The 0.50kg ball moves backward at 14.0 ms-1 after the

collision. Find the velocity of the second ball after collision.

Answer:

m1 = 0.5 kg

m2 = 1.0 kg

u1 = 6.0 ms-1 

u2 = -12.0 ms-1

v1 = -14.0 ms-1 

v2 = ?

(IMPORTANT: velocity is negative when the object move in opposite siredtion)

According to the principle of conservation of momentum,

m1u1 + m2u2 = m1v1 + m2v2

(0.5)(6) + (1.0)(-12) = (0.5)(-14) + (1.0)v2

-9 = - 7 + 1v2

v2 = -2 ms-1

 

Card 4: What is elastic collision?

Elastic Collision

Elastic collision is the collision where the kinetic energy is conserved after the

collision.

Total Kinetic Energy before Collision

= Total Kinetic Energy after Collision

Additional notes:

-In an elastic collision, the 2 objects seperated right after the collision, and

-the momentum is conserved after the collision.

Previous | Top | NextCard 5: What is inelastic collision?

Inelastic Collision

Inelastic collision is the collision where the kinetic energy is not conserved after the

collision.

Additional notes:

-In a perfectly elastic collision, the 2 objects attach together after the collision, and

-the momentum is also conserved after the collision.

Previous | Top | NextExample 4:   Perfectly Inelastic Collision

A lorry of mass 8000kg is moving with a velocity of 30 ms-1. The lorry is then accidentally

collides with a car of mass 1500kg moving in the same direction with a velocity of 20 ms-1.

After the collision, both the vehicles attach together and move with a speed of velocity v. Find

the value of v.

Answer:

(IMPORTANT: When 2 object attach together, they move with same speed.)

m1 = 8000kg

m2 = 1500kg

u1 = 30 ms-1 

u2 = 20 ms-1 

v1 = v

v2 = v

According to the principle of conservation of momentum,

m1u1 + m2u2 = m1v1 + m2v2

(8,000)(30) + (1,500)(20) = (8,000)v+ (1,500)v

270,000 = 9500v

v = 28.42 ms-1

 

Card 6: Application of conservation of momentum 1 - Rocket

Rocket1. Mixture of hydrogen and oxygen fuels burn in the combustion chamber.

2. Hot gases are expelled through the exhausts at very high speed .

3. The high-speed hot gas produce a high momentum backwards.

4. By conservation of momentum, an equal and opposite momentum is

produced and acted on the rocket, pushing the rocket upwards.

Previous | Top | NextCard 7: Application of conservation of momentum 1 - Jet Engine

Jet Engine1. Air is taken in from the front and is compressed by the compressor.

2. Fuel is injected and burnt with the compressed air in the combustion

chamber.

3. The hot gas is forced through the engine to turn the turbine blade, which

turns the compressor.

4. High-speed hot gases are ejected from the back with high momentum.

5. This produces an equal and opposite momentum to push the jet plane

forward.

Effects of Force

Card 1: Newton's Second Law

Newton's Second Law

The rate of change of momentum of a body isdirectly proportional to

the resultant force acting on the body and is in the same direction.

Implication:

When there is resultant force acting on an object, the object

will accelerate (moving faster, moving slower or change direction).

Top | NextCard 2: Force

Force A force is push or pull exerted on an object.

Force is a vector quantity that has magnitude and direction.

The unit of force is Newton ( or kgms-2).

Previous | Top | NextCard 3: Formula of Force

Formula of Force

From Newton's Second Law, we can derived the equation

(IMPORTANT: F Must be the net force)

Previous | Top | NextCard 4: Summary of Newton's 1st Law and 2nd Law

Summary of Newton's 1st Law and 2nd Law

Newton's First Law:

When there is no net force acting on an object, the object is either stationary or

move with constant speed in a straight line.

Newton's Second Law:

When there is a net force acting on an object, the object will accelerate.

Previous | Top | NextExample 1

A box of mass 150kg is placed on a horizontal floor with a smooth surface; find the acceleration

of the box when a 300N force is acting on the box horizontally.

Answer:

F = ma

(300) = (150)a

a = 2 ms-2

Example 2

A object of mass 50kg is placed on a horizontal floor with a smooth surface. If the velocity of

the object changes from stationary to 25.0 m/s in 5 seconds when is acted by a force, find the

magnitude of the force that is acting?

Answer:

We know that we can find the magnitude of a force by using the formula F = ma. The mass m

is already given in the question, but the acceleration is not give directly.

We can determine the acceleration from the formula

\begin{gathered}

a = \frac{{v - u}}

{t} \hfill \\

a = \frac{{25 - 0}}

{5} = 5ms^{ - 2} \hfill \\

\end{gathered}

From the formula

F = ma = (50)(5) = 250N

The force acting on the box is 250N.

 

Card 5: Effects of Force

Effects of Force

When a force acts on an object, the effect can change the

size,

shape,

stationary state,

speed and

direction of the object.

Previous | Top | Next