OBJECTIVE 5:THE STUDENT WILL DEMONSTRATE AN UNDERSTANDING OF MOTION, FORCES, AND ENERGY.

Basic Physics

Knows concepts of force and motion evident in everyday life.

Motion and Forces

Calculate speed, momentum, acceleration, work, and power in systems such as in the human body, moving toys, and machines.

Investigate and describe applications of Newton's laws such as in vehicle restraints, sports activities, geological processes, and satellite orbits.

Investigate and demonstrate [mechanical advantage and] efficiency of various machines such as levers, motors, wheels and axles, pulleys, and ramps.

Equations

There are many equations you need to know how to use.

You will get a formula sheet with constants. Be sure you know how to use it and are familiar with it.

Speed and Velocity

How fast you change your position.

Units: t’s

up. Speed & velocity: m/s or cm/s or

km/hr Distance: m or cm or km Time: seconds (s) or hours (h)

Acceleration

Acceleration is the rate of change of velocity.

It occurs when an object changes its speed, its direction or both.

Units: Acceleration: m/s/s or m/s2

Velocity: m/s Time: s

Force

Force is a push or pull that makes things move (accelerate). This is Newton’s second law and the force is the net force.

Units: Force: Newtons (N) sometimes (n) Mass: kg Acceleration: m/s/s or m/s2

Newton’s First law of Motion

An object in motion will stay in motion and an object at rest will stay at rest unless acted upon by an external force.

A body persists in a state of uniform motion or of rest unless acted upon by an external force.

A body keeps doing what its doing unless forced to change.

AKA: the law of inertia.

Newton’s Second Law of Motion:

Force = mass x acceleration (this is a formula) Force equals mass times acceleration. net F = ma (formula sheet) AKA: F = ma With equal force…

a smaller mass object will accelerate at a large rate a big mass will accelerate at a small rate.

With equal masses… a larger force will accelerate it at a faster rate a small force will accelerate it at a smaller rate.

Weight

You use Newton’s second law to calculate something’s weight.

The acceleration you would use is the acceleration due to gravity; 9.8 m/s/s This is given to you on the formula sheet.

Weight = mass (in kilograms) x 9.8 m/s/s

Your weight would be in Newtons (N)

Newton’s Third Law of Motion:

For every action there is an equal and opposite reaction.

AKA: Action – Reaction Law Action – Reaction Pairs.

Action: Joe hits Jack Reaction: Jack hits Joe

Action: Bob pulls on box Reaction: Box pulls on Bob

Action: Earth pulls on Moon Reaction: Moon Pulls on Earth

Gravity

The pull of gravity depends on the size of the objects (masses) and the distance between their centers.

This is explained by Newton’s Universal Law of Gravity. There is gravity between all objects in the universe.

Increasing the masses of one or both objects increases the force between them.

Increasing the distance between their centers, decreases the force of gravity (by a square).

Gravity and Circles

Objects travel in a circle because something holds it in orbit.

This force is the pull of gravity. It is caused by the two objects in

question and the distance between them.

The pull of gravity is everywhere.

Momentum, p

Momentum is moving mass. Momentum is mass times its velocity. Momentum, p, is measured in either:

kg m/s or g cm /s There is a formula for momentum.

Momentum

Momentum is a concept of moving mass.

Units: Momentum: kg m/s or g cm/s Mass: kilograms (kg) or grams (g) Velocity: m/s or cm/s

Conservation of Momentum

The total momentum before equals the total momentum after.

In dealing with momentum, directions matter.

Conservation of Momentum

The total momentum before a happening or collision equals the total momentum after.

You find the mv of each object before a collision and the mv of each object after and they must be equal.

Momentum is a vector so its direction matters. The direction of the momentum is the same direction as its velocity.

They like momentum problems.

Knows the impact of energy transformations in everyday life.

Energy

Describe the law of conservation of energy.

Investigate and demonstrate the movement of heat through solids, liquids, and gases by convection, conduction, and radiation.

Investigate and compare economic and environmental impacts of using various energy sources such as rechargeable or disposable batteries and solar cells.

Convection

A form of heat transfer through liquids and gases (fluids).

Heat is transferred by currents in the fluids.

Heat moved by fluid motion.

Conduction

Heat transferred by vibrating neighboring molecules.

Heat transferred through solids. Heat moves from hot to cold.

Radiation

Heat transferred by waves. Heat from our Sun reaches us through

waves.

Work, W

Work is defined as force acting over a distance.

The force must move the object. There is a formula for work. Work, W , is measured in Joules, J.

Work

Work is force acting over a distance. The force must move the object.

Units: Work Joules (J) sometimes (j) Force: N Distance: m

Kinetic Energy

Energy of motion. If an object is moving it has kinetic

energy. There is a formula for kinetic energy. Energy is measured in Joules, J.

Kinetic Energy

Energy due to motion.

Units: KE: Joules (J) Mass: kg Velocity: m/s

Potential Energy

Potential energy is stored energy. For TAKS, It is energy due to an object’s

height. There is a formula for potential energy. Energy is measured in Joules, J. Changes in potential energies are

important.

Gravitational Potential Energy

Energy due to its position and the pull of gravity.

Units: PE: Joules (J) Mass: kg Acceleration due to gravity: 9.8 m/s/s Height: m

Conservation of Energy

The total energy before equals the total energy after.

Energy can change forms. Work is a form of energy.

Conservation of Energy

Energy must be accounted for. Energy can change forms from Potential

Energy to Kinetic Energy and back again. The total amount of energy a system can have can change by doing work in the system.

The total energy of a system equals a constant.

Energy can be lost to: Work done by friction and lost to heat.

KE + PE at one place = KE + PE at another place

Power; Mechanical

Power is how fast work is done or how fast energy is generated or used up (dissipated).

Units: t’s

up. Power: Watts (W) or kiloWatts kW Work: J Time: s

Machines A machine is a device that

takes work (force x distance) and increases the applied force by decreasing the distance. It’s a trade off. You always need more input work than you get out because some work goes to overcome friction and heat.

There is no such thing as a 100% efficient machine.

You never get out more than you put in.

Simple machines Lever Pulley Screw Inclined

plane Wedge Wheel

and Axle

Which lever would require the least effort to lift the box ?

A C

B D

Levers

load distance distance force

fulcrum or pivotIf in balance: load x distance = distance x force

Efficiency: Machines

A percentage of how much work you do goes into doing the job.

Units: Efficiency is a %, no units Work: J

The 6 Simple Machines

Energy - Mass

This is the connection between mass and energy. Einstein’s equation.

Units: Energy: Joules (J) Mass: kg c = 3 x 108 m/s

Knows the effects of waves on everyday life.

Waves

Demonstrate wave interactions including interference, polarization, reflection, refraction, and resonance within various materials.

Wave

A wave is a disturbance (energy) carried through a material medium. (mechanical wave)

Light is an electromagnetic wave. It does not need a material medium to travel through.

There are two types of mechanical waves: Transverse waves are made perpendicular

to the medium. Longitudinal waves are made parallel to the

medium.

Wave Equation

This is the equation you use with waves.

Units: Velocity: m/s Frequency: Hertz (Hz) Wavelength: m

Wave Parts

Frequency, f

Frequency, f , is how many things happen in one second.

How many waves are made in 1 second. Frequency , f , is measured in Hertz, Hz.

Period, T

The amount of time it takes to do something once.

The amount of time to make one wave. Period, T , is measured in seconds, s.

Wavelength, λ

The length of one wave is called the wavelength.

It’s the distance from crest to crest, trough to trough, or from corresponding part to like corresponding part.

Wavelength, λ , is .measured in meters, m

Amplitude

The height of a wave from equilibrium, or the depth of the wave from equilibrium.

Amplitude is usually measured in meters, m.

Medium

The stuff that carries the wave. Sound travels in air. Water waves travel in water. Earth quakes travel in dirt (earth) Light travels in empty space (light

is an electromagnetic wave and does not need a medium)

Wave Properties

Reflection

When a wave hits a barrier it bounces off at the same angle it hits the surface.

When you look in the mirror you see your reflection.

The law of reflection is the angle of the incoming ray equals the angle of the out going ray.

Refraction

When a light ray changes mediums it bends. The bending of alight ray is refraction.

When a wave changes mediums it refracts.

The change of direction of a ray of light, sound, heat, or the like in passing from one medium into another due to the change in the speed of the wave.

Diffraction

The change in a wave as it passes by an obstacle or through an opening.

The spreading out of a wave as it passes by a barrier.

Resonance

Also called sympathetic vibrations. Something starts to vibrate or shake

because something else is vibrating.

Sound

Sound is a longitudinal wave. It travels at around 340 m/s (constants

chart) The note or pitch of a sound wave is its

frequency. The loudness of the sound wave is its

amplitude. Sound needs a medium to travel through,

this medium is air. Sound are waves that our ears can pick up.

Light

Light is a transverse wave. It is also an electromagnetic wave.

Light does not need a medium to travel through.

It travels at a maximum speed of 3 x 108 m/s, the speed of light (constants chart)

This speed is also called c. White light has all the colors in the

rainbow. Roy G Biv.

Light

The primary colors of light are Red, Green, & Blue. RGB

Light colors are different frequencies (or wavelengths) of light.

Light we see is called the visible spectrum.

Light wavelengths are very small.

Electricity

Electric Circuits

An electric circuit has three basic parts: A source of electricity : a battery or outlet (voltage) Connectors that carry the electricity in a closed loop;

wires Objects that use electricity, resistors, light bulbs, etc.

The devices that use electricity and be connected: In series, one after the other. In parallel, there are multiple pathways (loops)

There must be a closed loop from one end (+ pole) of the battery to the other end (− pole)

Series Circuits

When a circuit is connected in series; The electrons coming out of the battery

must pass through each device. If the pathway is broken, all devices stop

working. The voltage is divided up with each device

in the circuit. The current (amps) is the same throughout

the circuit.

Series Circuits

Parallel Circuits

When a circuit is connected in parallel: There are multiple pathways for electricity to

travel. Each device gets the same voltage, equal to the

voltage of the battery. The current coming out of the battery divides

and takes separate paths to the other side of the battery.

If one device goes out, the rest can stay on. Most Christmas lights are connected in parallel. Houses are wired in parallel.

Parallel Circuits

Electrical

Current (I) , Voltage (V), Resistance (R)

R’s up. Units

Current: Amperes (A) Voltage: Volts (V) Resistance: Ohms ()

Ohms Law Applied

Electrical Power

How fast electricity is used (dissipated) or made (generated)

Units: Power: Watts (W) Voltage: Volts (V) Current: Amperes (A)

Electrical Energy

Energy due to electricity

Units: Energy: Joules (J) Power: Watts (W) Time: s

You must account for everything.The before equals the after.

Conservation Laws

Conservation of Mass

The total mass before equals the total mass after.

Mass cannot be created or destroyed.

Conservation of Momentum

The total momentum before equals the total momentum after.

In dealing with momentum, directions matter.

Conservation of Energy

The total energy before equals the total energy after.

Energy can change forms. Work is a form of energy.

Units:

Length or distance (d): meters m kilometers km centimeters cm millimeters mm

Density

How much stuff is crammed into a volume. How much mass is in a confined space.

Units: V’s up. Density: g/cm3 g/mL kg/m3 kg/L Mass: grams (g) kilograms (kg) Volume: liters (L) milliLiters (mL) cubic

meters (m3) cubic centimeters (cm3)

Heat

Heat gained or lost. Heat is a form of energy.

Units: Heat: calories (cal) Calorie (Cal) kilocalorie

(kcal) Mass: grams (g) or kilograms (kg) Temperature: Celsius or centigrade (°C) Specific heat: should be given

Units:

Time (t) seconds s hours h minutes min

Mass (m) kilograms kg grams g

Units:

Volume (V) Solid:

cubic meters m3

cubic centimeter cm3

Liquids: liters L ; l milliliters mL ; ml

Units:

Force (F) Newtons N

Work (W); Energy (E) , (KE) and (PE) Joules J

Power (P) Watts W kilowatts kW

Units:

Frequency (f) Hertz Hz

Electricity Voltage (V) Volts V Current (I) Amperes ; Amps

A Resistance (R) Ohms

Units:

Density (D) mass per volume kg/m3 g/cm3 kg/L g/mL

Velocity (v) speed distance per time m/s km/h cm/s

Acceleration (a) distance per time per time m/s/s m/s2 cm/s/s cm/s2

Units:

Momentum (p) mass times velocity kg m/s g m/s g cm/s

Work (W) Force times distance N m J

Power (P) Work per time N m/s J/s W

Units:

Heat (Q) calories cal Joules J

Acceleration due to gravity (g) 9.8 m/s2