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PHSYICS

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

PHSYICS

- 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

BASIC QUANTITIES

Length: locates position of a point in space

Time: succession of events

Mass: amount of matter in a body

- 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

- 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

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

- 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.

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.

A. Four primary directions

B. Cartesian Plane

- 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

- 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)

- 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

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

- Vf = Vi + at
- D = Vit + 1/2at2
- Vf2 = Vi2 + 2ad

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?

- 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.

- 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.

- 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

- 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.

- Projectile motion: motion in two dimensions
Horizontal (x-axis) component of motion

X = Vicosθt

Vertical (y-axis) component of motion

Y = Visinθt + 1/2gt2

- 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

- 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

- 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

- 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 = Force x Distance

Power = Work / Time

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

- 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

Ohm’s Law

V = IR

I – Current; unit: ampere (A)

V – Voltage; unit: volt (V)

R – Resistance; unit: ohm (Ω)

- Series: current is constant; voltage adds up

- Parallel: current adds up; voltage is constant

- 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

- 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

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