Phsyics
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Is a branch of science that deals with the properties, behavior and interaction between matter and energy. PHSYICS. Subdivisions of Physics. Classical Mechanics : study of motions based on Newton’s laws of mechanics

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PHSYICS

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Phsyics

Is a branch of science that deals with the properties, behavior and interaction between matter and energy

PHSYICS


Subdivisions of physics

Subdivisions of Physics

  • Classical Mechanics: study of motions based on Newton’s laws of mechanics

  • Thermodynamics & Statistical Mechanics: study of energy conversion involving heat and other forms of energy

  • Electromagnetism: interaction of electricity and magnetism, affecting presence/motion of particles

  • Relativity: relationship of electromagnetism and mechanics

  • Quantum Mechanics: atomic and subatomic systems and their interaction w/ radiation


Measurements how far how large how much

MeasurementsHow far? How large? How much?

BASIC QUANTITIES

Length: locates position of a point in space

Time: succession of events

Mass: amount of matter in a body


Derived quantities

DERIVED QUANTITIES

  • Volume: amount of space an object takes up

EXAMPLE:

What is the volume of a cylinder which has a diameter of 6 cm and a height of 5 cm?

Formula: V = ∏r2h

Answer: 45 ∏ cm3


Phsyics

  • Density: mass of an object per unit volume

    EXAMPLE

    What is the density of a 40 ft x 25 ft x 10 ft rectangular prism if it has a mass of 50000 grams?

    D = mass/volume

    Answer: 5 g/ft3


Units of measurement

UNITS OF MEASUREMENT


Conversion of units

Conversion of Units


Phsyics

How many mililiters are there in 3.45 L?

Answer: 3450 ml

Try these:

20 seconds = ? hours

10 m/s = ? km/h

10 cm3 = ? m3


Significant digits

SIGNIFICANT DIGITS

  • Nonzero digits are always significant.

  • All final zeroes after decimal points are significant.

  • Zeroes between two other significant digits are always significant.

  • Zeroes used solely for spacing decimal points are not significant.


Scalars quantities described by magnitude alone

SCALARSQuantities described by magnitude alone.

i.e. Length, mass, time, speed, energy, temperature, etc.

VECTORSQuantities described by both magnitude and direction.

i.e. Position, force, displacement, velocity, acceleration, torque, momentum ,etc.


Sense and direction of vectors can be represented in two ways

Sense and Directionof vectors can be represented in two ways.

A. Four primary directions


Sense and direction of vectors can be represented in two ways1

Sense and Directionof vectors can be represented in two ways.

B. Cartesian Plane


Mechanics branch of physics concerning the motions of objects and their response to forces

MECHANICSBRANCH OF PHYSICS CONCERNING THE MOTIONS OF OBJECTS AND THEIR RESPONSE TO FORCES.

  • DISTANCE: scalar; how much ground an object can cover during its motion

  • DISPLACEMENT: vector; how far out of place an object is

    Displacement = final position – initial position


Phsyics

  • SPEED: scalar; how fast an object is moving

  • VELOCITY: vector; rate at which an object changes its position

    Average speed = distance travelled/elapsed time

    (s=d/t)

    Average velocity = ∆ in position/elapsed time

    (v=∆d/ ∆t)


Phsyics

  • Acceleration: vector; change in velocity over a time interval

  • Positive direction of motion: acceleration

  • Negative direction: deceleration

    A = (final velocity – initial velocity)/ elapsed time

    A = ∆V/ ∆T


Phsyics

What is the average speed of a car that travels 330 km in 11 hours?

s = d/t = 330 km/11hrs = 30 km/hr

A cart accelerates from 88 m/s to 121 m/s in 11 s. What is its acceleration?

A = ∆v/ ∆t = (121-88)/11 = 3 m/s2


Uniformly accelerated motion uam

Uniformly Accelerated Motion(UAM)

  • Vf = Vi + at

  • D = Vit + 1/2at2

  • Vf2 = Vi2 + 2ad


Phsyics

An automobile is moving at 5 m/s and accelerates at 0.5 m/s2.

What is the velocity after 20 s? What is the distance travelled by the car?


Phsyics

  • FREE FALL – uniformly accelerated motion under the sole influence of gravity.

    A = 9.8 m/s2 downward

    Downward gravitational acceleration is indicatedby making acceleration negative.


Newton s laws of motion

NEWTON’S LAWS OF MOTION

  • Law of Inertia

  • an object at rest will stay at rest, and an object in motion will stay in motion, unless it is compelled to change that state by external forces.

    Inertia: property of matter that resists changes in motion

    Mechanical Equilibrium: achieved when sum of all forces acting upon an object is zero.


Phsyics

  • Law of Acceleration

  • The acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass

    A = force / mass

    Force: push or pull done on an object that changes its state of motion


Phsyics

  • Law of Interaction

  • Every action elicits an equal and opposite reaction

    FREE BODY DIAGRAMS

    SHOW RELATIVE MAGNITUDE AND DIRECTION OF ALL FORCES ACTING UPON AN OBJECT IN A GIVEN SITUATION.


Special topics

SPECIAL TOPICS

  • Projectile motion: motion in two dimensions

    Horizontal (x-axis) component of motion

    X = Vicosθt

    Vertical (y-axis) component of motion

    Y = Visinθt + 1/2gt2


Phsyics

  • Uniform Circular Motion: motion in a circular path

    - velocity changes in direction yet the magnitude remains constant, thus motion is accelerate

    - direction of acceleration is inward due to centripetal force


Phsyics

  • Torque: tendency of a force to rotate an object about some axis

    Torque = FI

    *where F = force applied perpendicularly; I = distance of applied force from fulcrum/axis

    Linear Momentum and Collisions

    P = mass x velocity = mv

    *where P = momentum


Energy

ENERGY

  • Law of conservation of energy

  • Energy can neither be created nor destroyed.

    MECHANICAL ENERGY: energy possessed by a body due to its position (Potential energy) or motion (Kinetic energy)

    ME = PE + KE


Energy1

ENERGY

  • Potential Energy (PE) – energy possessed by a body due to its position, shape, and configuration

    PE = mgh

  • Kinetic Energy (KE) – energy of motion

    KE = 1/2mv2


Work and power

Work and Power

Work = Force x Distance

Power = Work / Time

*unit for power is the Joule/second or simply watt.


Waves

WAVES

  • A disturbance that travels through a medium, transporting energy to another location without transporting matter

  • Transverse: particles move perpendicular to the direction of the wave

  • Longitudinal: particles move parallel to direction of the wave

  • Surface: particles undergo a circular motion


Wave properties

WAVE PROPERTIES


Electricity

ELECTRICITY

Ohm’s Law

V = IR

I – Current; unit: ampere (A)

V – Voltage; unit: volt (V)

R – Resistance; unit: ohm (Ω)


Electric circuits

ELECTRIC CIRCUITS

  • Series: current is constant; voltage adds up


Phsyics

  • Parallel: current adds up; voltage is constant


Optics

OPTICS

  • Reflection: change in direction of a light ray in an interface with dissimilar media so that the wave returns into the medium from which it originated

    Law of Reflection

    Angle of incidence = Angle of reflection


Phsyics

  • Refraction: change in direction of a wave due to a change in its speed when passing through a different medium

    Law of Refraction

    n1sinθ1 = n2sinθ2


Plane mirros

PLANE MIRROS

Image characteristics: virtual, upright, same distance from the mirror as the object’s distance, same size as the object


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