TAKS Review — Formulas Integrated Physics and Chemistry

TAKS Review - Formulas Integrated Physics and Chemistry (4) Science Concepts. The student knows concepts of force and motion evident in everyday life. The student is expected to: (A) calculate speed, momentum, acceleration, work, and power in systems such as in the human body, moving toys, and machines;

Common measurements and symbols Measurement Symbol Typical Units on TAKS speed or velocity v m/s momentum p kg. m/s acceleration a m/s 2 Work W J Power p W Force F N Time t s Mass m kg E, KE or PE J Energy

Using the formula chart 1. Circle what you are asked to find 2. Underline given facts with numbers and units and write the symbol above it. 3. Identify the formula(s) you will use from the formula chart 4. Rearrange the formula for what you’re asked to find. 5. Put in numbers for symbols and solve. 6. Check that you answered the question asked.

Rearranging formulas When a formula is not solved for the variable you are trying to find, then you need to rearrange it until your variable is alone on one side of the equation.

Rearranging formulas Example, the speed formula is: If you are given speed and time and want to find distance, what would the formula be?

Rearranging formulas Here, you divided d by t. To move t to the other side, do the opposite, multiply by it. t cancels on the right side And you are left with the formula for d.

Speed and Velocity How fast an object is traveling. Velocity has direction, speed does not.

Acceleration The change in velocity Can be: • speeding up • slowing down • or changing direction If an object is moving at a constant speed, acceleration = 0 Negative acceleration (deceleration) means the object is slowing down.

Work Using force to move an object a certain distance. If there is no movement, there is no work done. If distance = 0, work = 0 The displacement must be in the direction of the force. Does not depend on the time it takes to do the work

If Distance = 0, then Work = 0.

The man is carrying his groceries 2 meters to the counter. He is holding the groceries with a force of 10 N, what is the work done on the groceries? The force and the displacement are not in the same direction. Therefore, Distance = 0, Work = 0. If the man had been lifting the groceries up, then there would be work.

Power The rate at which work is done. More power means the same work can be done faster.

How could this person increase his power?

What is the power of this motor? Power = Work/time Time = 5 s We must find the work first! Work = Force x distance = 10 N x 2 m = 20 J Power = Work/time = 20 J/5 s =4 Watts

Momentum The product of an object’s mass and velocity. Can be thought of as how difficult it is to stop a moving object. A stopped object has zero momentum.

Conservation of Momentum In collisions, total momentum does not change. The momentum of the objects (together) before the collision is the same as the momentum of the objects (together) after the collision.

Distance vs. Time graphs • In a distance vs. time graph, the slope of the line is the speed of the object. • If you have a horizontal line, the object is stopped.

No speed = stopped

Constant speed away from a point Constant speed toward a point

The line gets steeper – speeding up The line gets less steep – slowing down

Velocity vs. Time Graphs • In a velocity vs. time graph, the slope of the line is the acceleration of the object. • In this type of graph, a horizontal line means that the object is moving at a constant speed.

• 1. A ball moving at 30 m/s has a momentum of 15 kg·m/s. The mass of the ball is — A 45 kg B 15 kg C 2. 0 kg D 0. 5 kg

• 2. The weight lifter used a force of 980 N to raise the barbell over head in 5. 21 seconds. Approximately how much work did she do in raising the barbell? F 380 J G 982 J H 2, 000 J J 10, 000 J

3. How much work is performed when a 50 kg crate is pushed 15 m with a force of 20 N? F 300 J G 750 J H 1, 000 J J 15, 000 J

4. According to this graph, what was the bicycle’s acceleration between 6 and 10 seconds? A 0. 0 m/s 2 B 0. 65 m/s 2 C 1. 6 m/s 2 D 6. 5 m/s 2

5. If a force of 100 newtons was exerted on an object and no work was done, the object must have — A accelerated rapidly B remained motionless C decreased its velocity D gained momentum

6. A mechanic used a hydraulic lift to raise a 12, 054 N car 1. 89 m above the floor of a garage. It took 4. 75 s to raise the car. What was the power output of the lift? A 489 W B 1815 W C 4796 W D 30, 294 W

7.

• 9. The pictures show an air bag functions in a collision. How much momentum in kg. m/s does the air bag absorb from the crash-test dummy if all of the crash-test dummy’s momentum is absorbed by the air bag? P = m x v = 100 kg x 6. 3 m/s = 630 kg x m/s

Integrated Physics and Chemistry (4) Science Concepts. The student knows concepts of force and motion evident in everyday life. The student is expected to: (B) Investigate and describe [applications of] Newton’s laws such as in vehicle restraints, sports activities, geological processes, and satellite orbits.

Forces • Force can be defined as a push or a pull. • Forces can be balanced, which mean they are equal and opposite with no change in direction. If the forces on an object are balanced, it will either remain at rest or it will move at a constant speed in a straight line.

Unbalanced forces cause an object to accelerate (speed up, slow down or change direction) in the direction of the largest force.

Friction is a force that acts in the opposite direction to the motion of a moving object.

Newton’s Laws Newton’s First Law: An object at rest will remain at rest and an object in motion will remain in motion at a constant velocity unless acted upon by an unbalanced force. • The Law of Inertia.

Orbits and Inertia

Newton’s Second Law: • Force = mass x acceleration • For a constant force, if mass increases acceleration decreases • For a constant mass, if force increases, acceleration increases

The force on the ball and the force on the cannon are equal (See 3 rd Law). F = ma The ball’s mass is lower, so its acceleration is higher. The cannon’s mass is greater, so its acceleration is lower.

Newton’s Third Law: For every action force, there is an equal and opposite reaction force.

1. Which of these is the best description of the action- reaction force pair when the space shuttle lifts off from the launchpad? A The ground pushes the rocket up while exhaust gases push down on the ground. B Exhaust gases push down on air while the air pushes up on the rocket. C The rocket pushes exhaust gases down while the exhaust gases push the rocket up. D Gravity pulls the rocket exhaust down while friction pushes up against the atmosphere.

2. After shooting a cannonball, a cannon recoils with a much lower velocity than the cannonball. This is primarily because, compared to the cannonball, the cannon has a — F much greater mass G smaller amount of momentum H greater kinetic energy J smaller force applied to it

3. How many newtons of force does a 50. 0 kg deer exert on the ground because of gravity? F = m x a 50 kg x 9. 8 m/s 2 = 490 N

4. Which factor would most likely cause a communications satellite orbiting Earth to return to Earth from its orbit? F An increase in the satellite’s forward momentum G An increase in solar energy striking the satellite H A decrease in the satellite’s size J A decrease in the satellite’s velocity

TAKS Review: Simple machines (D) investigate and demonstrate [mechanical advantage and] efficiency of various machines such as levers, motors, wheels and axles, pulleys, and ramps. (11 th only)

Simple machines are tools that make work easier, usually do work with a single movement

Simple machines The amount of effort saved when using machines is called mechanical advantage or MA

Mechanical Advantage Mechanical advantage is how many times a machine multiplies the force that is put into it. For example, if you put in a force of 10 N, and the machine puts out a force of 40 N, then the machine has multiplied your force ___ times. The mechanical advantage is 4. (Remember Work remains the same!)

Mechanical advantage is calculated by the following formula: MA = Resistance force= Fr Effort force Fe

For example, if a worker applies a force of 20 N to pry out a nail that has a resistance force of 500 N, what is the mechanical advantage of the hammer the worker uses? MA = Resistance force = Fr = Effort force Fe = 25 500 N= 20 N

Ideal MA If you do not know the forces applied, the mechanical advantage a machine should provide (called ideal MA) can be calculated by the following formula: IMA = Effort distance Resistance distance

Pulleys The mechanical advantage of a pulley = the number of supporting strings. If you pull up on a string you count it. If you pull down on a string you don’t count it.

What is the MA? 3 2 4

Levers In a lever, the MA can be found by dividing the distance between the fulcrum and the effort by the distance between the fulcrum and resistance.

Levers So, to make a lever easier to use, move the fulcrum closer to the weight you are trying to move and further from where you are pushing.

Which is easiest to move?

Ramp To increase the MA of a ramp (to make the ramp easier to climb), make the ramp longer with a more gradual incline.

How could you make this ramp easier to climb?

Wheel and axle • To increase the MA of a wheel and axle, make the wheel larger and the axle smaller.

A gear system is a modified type of wheel and axle, where the larger gear acts as the wheel and the smaller gear acts like the axle. How could you change these gears to make the smaller one turn faster? Make the larger gear larger or the smaller gear smaller.

Efficiency • If a machine were perfect, all of the work that was put in would be used to do useful work. • In real life, some work put into a machine is “lost” as heat or friction. • We calculate efficiency to determine how much of the work put in actually produces useful work.

Efficiency • Efficiency = Work out x 100% Work in • If a machine were perfect and there were no friction, efficiency would be 100%, because all of the work in would become work that came out. • In real life, efficiency is always less than 100%!!!!

The diagram shows an electric motor lifting a 6 N block a distance of 3 m. The total amount of electrical energy used by the motor is 30 J. How much energy does the motor convert to heat? F 9 J G 12 J H 18 J J 21 J

Which lever arrangement requires the least effort force to raise a 500 N resistance?

What is the efficiency of an air conditioner if there is a work input of 320 J and a work output of 80 J? F 4% G 25% H 240% J 400%

Which configuration of pulleys and belts shown below will result in the fastest rotation of Spindle 2?

Integrated Physics and Chemistry (6) Science Concepts. The student knows the impact of energy transformations in everyday life. The student is expected to (A) describe the law of conservation of energy.

Energy • energy- the ability to do work • unit: joule (J)

Types of Energy: – kinetic energy- the energy of motion • the faster an object moves, the more kinetic energy KE = ½ (mv 2) – potential energy- energy of position • stored energy – ex: a ball rolled to the top of a hill • GPE is potential energy due to gravity. GPE = mgh (remember g = 9. 8 m/s 2)

law of conservation of energy • energy may neither be created nor destroyed • it can only be transformed into various forms—from kinetic to potential, from chemical to mechanical • the total energy in the system is constant

Where is the PE greatest? Where is the PE least? Where is the KE greatest? Where is the roller coaster moving the fastest?

Types of Energy mechanical energy- Moving objects heat energy- usually results from friction—causes phase & temperature changes chemical energy- stored in chemical bonds Example, released when starting a fire, burning fuel, digesting food nuclear energy- Nuclear reactions; produces the sun’s energy due to nuclear fusion--hydrogen changes to helium electromagnetic energy- Charges—microwaves, Xrays, light

Energy conversions

Energy conversions

Powerful Plankton The U. S. Naval Research Laboratory has created an experimental marine fuel cell that could produce enough electricity to power ocean-monitoring devices. This fuel cell runs on seawater and sediment, with the help of plankton. Some plankton on the surface of ocean sediments use dissolved oxygen to break down organic matter, releasing energy; this is an aerobic process. The plankton in the deeper sediments break down organic matter without using oxygen; this is an anaerobic process. These two processes create a difference in voltage between the surface of the sediment and the sediment farther down in the seabed. The voltage difference can be used to produce electricity-up to 5. 0 x 10 – 2 watts of power. Energy supplied by this type of fuel cell can be obtained as long as there is organic matter in the sediment. Fuel cells powered by plankton from the seabed can be used to operate instruments that monitor ocean currents and water temperature. These fuel cells get their energy by converting — F chemical energy to electrical energy G electrical energy to mechanical energy H hydroelectric energy to geothermal energy J mechanical energy to chemical energy

Which process best shows the conversion of solar energy to chemical energy? F Prevailing winds causing windmills to spin G Green plants making their own food H Uranium producing heat to make steam J Tides generating electricity

What is the potential energy of the rock? A 59, 900 joules B 64, 600 joules C 93, 100 joules D 121, 600 joules

Which of the following is an example of solar energy being converted into chemical energy? F Plants producing sugar during the day G Water evaporating and condensing in the water cycle H The sun unevenly heating Earth’s surface J Lava erupting from volcanoes for many days

An inventor claims to have created an internal combustion engine that converts 100 k. J of chemical energy from diesel fuel to 140 k. J of mechanical energy. This claim violates the law of conservation of — F momentum G inertia H energy J mass

Integrated Physics and Chemistry (6) Science Concepts. The student knows the impact of energy transformations in everyday life. The student is expected to (B) investigate and demonstrate the movement of heat through solids, liquids, and gases by convection, conduction, and radiation

Remember the properties of solids, liquids and gases…

• heat- energy caused by the internal motion of molecules • heat transfer- the movement of heat from a warmer object to a cooler one

3 methods of heat transfer 1. conduction- heat transferred by direct contact of molecules • takes place in solids, liquids, & gases, but does best in solids • one particle must contact another for this to occur. In solids, the particles are close to each other, which makes contact easier.

Conductors vs. Insulators conductors- substances that conduct heat better & more rapidly than others (silver, copper, iron) insulators- substances that do not conduct heat easily (glass, plastic, wood, rubber)—wearing several layers of clothing in extremely cold weather

3 Methods of Heat Transfer 2. convection- takes place in liquids & gases as up-and-down movements called convection currents. • Important: Does not occur in solids

Convection – look for arrows or circular motion

3 Methods of Heat Transfer 3. radiation- heat energy transfer through empty space • This is how the sun heats the earth

Which method is shown? Radiation Conduction

Which method is shown? Convection

Radiation/ Convection Radiation Convection/ Conduction

The primary way liquids and gases transmit heat is by the process of — A reflection B conduction C radiation D convection

A man who was sleeping wakes up because he hears the smoke alarm go off in his house. Before opening the bedroom door, the man feels the door to see whether it is warm. He is assuming that heat would be transferred through the door by Conduction _____________

A solar heater uses energy from the sun to heat water. The heater’s panel is painted black to — F improve emission of infrared radiation G reduce the heat loss by convection currents H improve absorption of infrared radiation J reduce the heater’s conducting properties

In which container is the substance unable to transfer heat by convection?

Container P and Container Q each were filled with 0. 5 liter of water. The water was heated to 90°C. The table shows the temperatures after both containers were allowed to cool for 3 minutes. Compared to Container Q, Container P is a better A conductor C radiator B absorber D insulator

TAKS Review: Waves The student knows the effects of waves on everyday life. The student is expected to (A) demonstrate wave types and their characteristics through a variety of activities such as modeling with ropes and coils, activating tuning forks, and interpreting data on seismic waves. (10 th only) (B) demonstrate wave interactions including interference, polarization, reflection, refraction, and resonance within various materials. (11 th only)

Types of Waves 1. Transverse 2. Longitudinal (compression)

Parts of a Wave

Calculating Wave Speed = Wavelength • Frequency Measured in Hz

Interference Constructive Destructive

Reflection Angle of incidence = Angle of reflection

Refraction is the bending of light as it passes from one medium to another.

Refraction Pencil appears bent in a glass of water. Spear fishing: the fish is actually lower than it appears to be.

Refraction A prism separates white light into its components

Diffraction When a wave meets an obstacle it bends around the obstacle.

Resonance occurs when two nearby objects share the same vibrational frequency. When one of the objects is vibrating, it forces the second object into vibrating. The result is a large vibration = a large sound (in sound waves)

Resonance Example: Two similar tuning forks. When one tuning fork is sounded, the second tuning fork is energized by the specific frequencies emitted by the first, and begins to vibrate and sound as well!

Other examples of resonance: • Plucked strings on musical instruments (guitar) • Air blown across a tube (flute) or bottle of water • Vocal cords

Polarization

At 0°C sound travels through air at a speed of 330 m/s. If a sound wave is produced with a wavelength of 0. 10 m, what is the wave’s frequency? F 0. 0033 Hz G 33 Hz H 330 Hz J 3300 Hz

• Which illustration best demonstrates compression waves?

Which wave has the greatest velocity?

When trying to spear a fish in water, a person needs to take into account the way light bends as it moves from water into air. The bending of light as it passes from one medium into another is known as — F reflection G refraction H diffraction J polarization

One tuning fork is struck and placed next to an identical fork. The two forks do not touch. The second tuning fork starts to vibrate because of — F interference G the Doppler effect H resonance J standing waves

The pitch of a sound made by plucking a guitar string is determined by the — A frequency of the vibration produced B strength of the plucking force C distance between the strings D shape of the guitar body

The diagram shows waves approaching a barrier. Which pattern will be formed after the waves pass through the opening in the barrier?

Electric Circuits IPC 6 F – Investigate and compare series and parallel circuits. (10 th grade only)

Circuits To have an electric circuit, you need: • a closed conducting path which extends from the positive terminal to the negative terminal. • An energy source, such as a battery.

Will the bulb light?

Will the bulb light? Closed loop!

Series circuit • each device is connected in a manner such that there is only one pathway by which charge can traverse the external circuit. What happens if the first light bulb burns out?

Parallel Circuits • multiple pathways by which charge can flow through the external circuit. What happens if the first light bulb burns out?

Circuit Math Voltage (Volts) Current (Amps) Resistance (Ώ)

Which switch, if opened, will cause the lightbulb to stop glowing? F Q GR HS JT

What is the current in a copper wire that has a resistance of 2 ohms and is connected to a 9 volt electrical source? F 0. 22 amp G 4. 5 amps H 11. 0 amps J 18. 0 amps

How much current is flowing through this circuit? A 0. 32 A B 3. 1 A C 4. 0 A D 12. 5 A

Which circuit is built so that if one lightbulb goes out, the other three lightbulbs will continue to glow?