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Objective 5 Review Quick Physics and Energy

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Physics is about Energy and Motion How and why do things move? Do planets move the same way as a ball that is thrown? These are the types of questions physics tries to answer.

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Quick physics Speed or Velocity = Distance / Time Acceleration = V final – V start / time to change Work (joules) = Force (Newton) x distance (meters) Power (watts) = Work / time

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A toy car moves 20 m in 40 seconds. What is the speed of this car? Distance / Time = Speed so 20m / 40s = 0.5 m/s or....

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An object is moving at 15 m/s and after 10 seconds the object is moving at 35 m/s. What is the acceleration of the object? Acceleration = V f – V i / Change in time so... 35m/s – 15m/s / 10 s = 2 m/s/s 2

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A young man is standing in line at the grocery store holding a 12-pack of Coke weighing 50 N in his arms which are 1.5 meters off the ground. How much work is he doing? a. 0 Joules b.6.25 Joules c.33.3 Joules d.75 Joules Work = force x distance = 50N x 1.5m Or = 75 Joules _

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Lakiesha, who weighs 550 Newtons, runs to the top of a staircase 5 m tall in 3.5 seconds. How much power is Lakiesha demonstrating? a. 385 Watts b. 559 Watts c. 786 Watts d Watts Power = Work/time but nothing here is in Joules Work = force x distance so... Power = 550N x 5m / 3.5 s = 9625 watts

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Sir Isaac Newton and the 3 Laws of Motion Considered one of the foremost physicists, Described the motion of all things in a gravity and friction free system. For each of the next slides, write at least 3 examples of each law in action...

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Newton’s FIRST Law Law of Inertia An object at rest or in motion remains that way until acted upon by an unbalanced force.

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Newton’s SECOND Law Force = Mass x Acceleration The greater the force on an object in a single direction the greater the acceleration in that direction will be.

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Newton’s THIRD Law Law of Action/Reaction For every action force there is an equal and opposite reaction force. Motion is the result of unbalanced forces on the same object.

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There are 6 simple machines Lever 1 st Class with the fulcrum in the middle 2 nd Class with the resistance in the middle 3 rd Class with the effort in the middle To determine the lever classes three, what is in the middle spells FRE. Pulley, Wheel and Axle, Inclined Plane, Wedge and Screw

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Mechanical Advantage and Efficiency, Why Not 100% ? Mechanical advantage is how much your force is multiplied by the machine Efficiency is Actual MA/Ideal MA Never 100% due to FRICTION Almost all energy that is not converted into work is converted into heat.

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Waves Transverse Waves vibrate 90 o from the direction of travel. All electromagnetic waves are in this group. Visible light and the color spectrum are all transverse waves. Water ripple waves and microwaves are also of this type Compression Waves move in the same direction as their vibration. Sound waves, caused by a disturbance, carried through a medium are of this type. Some types of earthquakes are also compression waves.

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The Electromagnetic Spectrum Gamma X rays Ultraviolet Visible Infrared Micro- TV/Radio Radiation Light Light Radiaion waves Waves Shortest to Longest Remember: Long – Low – Slow: Long wavelength is a low frequency and slow velocity.

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Which of the following waves would have the highest pitch and lowest volume? A B D C

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Speed = frequency x wavelength All radiant energy travels at the same speed. 3 x 10 8 meters/sec This is the speed of light through space. Radio waves and nuclear energy waves travel at the same velocity.

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A sound wave is traveling at 343 m/s and has a frequency of Hz, what is its wavelength? a m b. 1.5 m c m d m Speed = frequency x wavelength so 343 m/s = Hz x wavelength

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Light Spectrum Visible light is a small part of the electromagnetic spectrum. Red is the longest wavelength; Violet is the shortest wavelength in visible light. As wavelength increases, what happens to frequency? Answer: Decreases! ROYGBIVROYGBIV

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Waves move, so there can be interference... When something is an interference, it changes the path of movement. Constructive means it adds to the wave’s energy or amplitude Destructive cancels or decreases the wave’s amplitude

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The diagram shows waves approaching a barrier. Which pattern will be formed after the waves pass through the opening in the barrier? After passing through the barrier, it will spread back out and continue on the same path.

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Ohm’s Law Voltage = Current x Resistance Standard American Current – 15 or 20 Amps Power, measured in Watts is P = VI

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A 9 V battery is connected to a 6 Ohm resistor. How much current will flow through the circuit? a. 54 Amperes b. 15 Amperes c. 3 Amperes d. 1.5 Amperes Voltage = Current x Resistance 9V = Amperes x 6 ohms or 9V/6ohms =

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Which of the following electromagnets would be able to pick up the greatest number of paperclips if each one was connected to the same battery? A D C B More current from more wraps means a stronger magnet.

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In the diagram above, which poles of the magnets are interacting? a. A north and a south pole b. Two north poles c. Two south poles N What is the rule for charges and magnetic poles? LIKE REPELS LIKE! Since the N pole is marked, these must both be south.

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