Download Spring Semester Study Guide - 8th Grade Physical Science

Spring End of Semester Test Study Guide
Chapter 8 Work and Machines (pp. 208-229)
1. What must occur in order for work to be done?
a. In order for work to be done, the direction of force must be in the direction of motion of the
object.
2. What is work? Know your formula!
a. Work is a force acting over a distance.
b. Work = force x distance
3. What are the 3 ways that machines make work easier?
a. Machines make work easier by decreasing the amount of force need to move an object by
increasing the distance the object moves
b. Also machines can change the direction of the input force.
4. What is the difference between work input and work output?
a. Work input is the work that a person does to a machine. The work output is what the work
machine does to the object.
5. What is the difference between mechanical advantage and efficiency?
a. Mechanical advantage is how many times a machine multiplies force.
b. Mechanical efficiency is how well a machine performs work on an object.
6. Why can’t a machine be 100% efficient?
a. No machine can ever be 100% efficient because of friction.
7. Be able to identify the six types of simple machines and how they make work easier.
a. The six types of simple machines are: inclined plane, wedge, screw, pulley, lever and the
wheel and axel.
8. Be able to identify simple machines in a compound machine.
a. A compound machine is made of multiple simple machines. An example of this would be a
can opener because it consists of a wheel and axel, a wedge and it is a lever.
Chapter 9 Energy and Energy Resources (pp. 238-263)
1. How are work and energy related?
a. Energy is the ability to do work.
2. What is the difference between kinetic and potential energy. What is the formula for each?
a. Potential energy is the energy of an object due to its position;
i. GPE= weight X height.
b. Kinetic Energy is the energy of motion;
i. KE= (mv^2)/2
3. What are the 6 different forms of energy?
a. Mechanical, Thermal, Chemical, Electrical, Light (Electromagnetic), and Nuclear
4. Be able to describe and identify different energy conversions. For example, describe the energy
conversions in the use of a toaster or TV.
a. Toaster-Electrical-Heat
b. TV-Electrical -Light
5. What is the law of conservation of energy?
a. The law of conservation of energy states that energy can neither be created or destroyed
only changes form.
Chapter 10 Heat (pp. 272-287)
1. How does temperature relate to kinetic energy?
a. Temperature is the average kinetic energy of the particles in an object.
2. What are the temperatures for the freezing point and boiling point of water on different temperature
scales (Fahrenheit, Celsius and Kelvin)?
a. Freezing Points 32F, 0C, and 273K
b. Boiling Points 212F, 100C, and 373K
3. What is the difference between thermal energy and temperature?
a. Thermal is the total kinetic energy in the particles of an object and temperature is the
average kinetic energy in the particles of an object.
4. What is heat?
a. Heat is the transfer of thermal energy between objects that have different temperatures.
5. What is the difference between conduction, convection, and radiation?
a. Conduction is the transfer through direct contact.
b. Convection is the transfer in liquids and gases that moves in a circular pattern caused by
differing temperatures.
c. Radiation is the transfer of energy in all directions usually in the forms of electromagnetic
waves.
6. What is absolute zero?
a. The temperature at which all molecular motion stops is absolute zero. 0K
Chapter 20 The Energy of Waves (pp. 572-589)
1. How do waves transfer energy without transferring matter?
a. Waves create a vibration in the particle which is passed from one particle to the next,
moving the energy forward but not the particles.
2. What is the difference between a mechanical and electromagnetic wave?
a. Mechanical waves require a medium to travel through electromagnet waves do not.
3. What is the difference between a transverse and a longitudinal wave?
a. Transverse waves cause the particles in a medium to vibrate perpendicularly to the
direction of wave motion. Transverse waves have crests and troughs. Longitudinal waves
cause particles of the medium to vibrate parallel to the direction of the wave motion.
Longitudinal waves have compressions and rarefactions.
b.
4. Describe the four wave properties. (frequency, amplitude, wavelength and wave speed)
a. Frequency: the number of waves produced in one second
b. Amplitude: the height of the wave, indicator of the amount of energy the wave is carrying.
c. Wavelength: the distance from one point to the next corresponding point on a wave (ex.
crest to crest or trough to trough)
d. Wave speed is the distance a wave travels in a given amount of time.
5. Be able to identify how frequency and wavelength are related to the speed of a wave. What is the
formula for wave speed?
a. Wave speed = wavelength x frequency
6. Describe the following wave interactions: reflection, refraction, and diffraction.
a. Reflection occurs when a wave hits a barrier and bounces back. This will cause a change in
direction but no other wave properties will change.
b. Refraction occurs when a wave enters a new medium and bends due to a change in speed.
c. Diffraction occurs when a wave goes around a barrier. This will cause a change in
direction but no other wave properties will change.
Chapter 21 The Nature of Sound (pp. 598-621)
1. How do vibrations cause sound? How is sound transmitted through a medium?
a. A vibration is passing from particle to particle and you hear it as a sound when it reaches
your ear drum.
2. How does the speed of sound in different media change?
a. Sound travels fastest in solids then liquids then gases.
b. Sound travels faster in warmer mediums than colder (when looking at one state of matter)
c. Sound travels faster in less dense mediums (when looking at one state of matter)
3. How are frequency and pitch related?
a. Frequency determines pitch. Higher frequency means higher pitch, lower frequency
means lower pitch.
4. How are amplitude, intensity and loudness related?
a. Amplitude determines volume, higher amplitude means a higher volume and lower
amplitude means a lower volume.
b. Intensity refers to the amount of energy the wave is carrying, the higher the energy the
higher the intensity, amplitude and volume.
5. What is the Doppler Effect and what is an example of it?
a. The Doppler effect is the change in pitch you hear as an object moves past you. An
approaching siren will sound higher than one that has past you.
6. What are echoes and how are they used in locating objects? (sonar and echolocation)
a. An echo is a reflected sound wave.
b. Sonar is technology humans use to find how far away things such as the ocean floor are.
c. Echolocation is used by bats and dolphins to locate objects.
Chapter 22 The Nature of Light (pp. 630-657)
1. What is an electromagnetic wave?
a. Light is an EM wave made up of alternating electric and magnetic fields.
2. How are the various parts of the electromagnetic spectrum different from each other?
a. The spectrum is ordered by decreasing wavelength and increasing frequency (increasing
energy).
Radio- Micro- InfraredVisible- UVx-rayGamma
Ex. TV- Cell phone- Warm things – Rainbow- sunburn- see inside- kills cells
3. Be able to describe the different interactions of light waves give an example of each. (reflection,
refraction, and diffraction)
a. Reflection- strikes a barrier and bounces back
b. Refraction – wave changes mediums and therefore speed so it bends (causes rainbow in
prism)
c. Diffraction – bending of a light around a barrier.
d. Interference – when 2 waves become 1
4. What happens to light during absorption and scattering?
a. Absorption- light energy is transferred to particles of matter and converted to heat
(causes light to dim)
b. Scattering – light waves hit particles and are scattered in all directions (causes the sky to
be blue)
5. What is the difference between transparent, translucent and opaque matter.
a. Transparent- light is easily transmitted and you can clearly see things on the other side
(clear glass window)
b. Translucent- light is transmitted and scattered so objects on the other side appear
scattered (wax paper)
c. Opaque- does not transmit light (aluminum foil).
6. How is the color of an opaque object determined? A transparent object?
a. The color that shows is reflected of the opaque object and all the other colors are
absorbed.
b. The color that shows is transmitted through the transparent object. The transparent
object absorbs all the other colors.
Chapter 23 Light and Our World (pp. 668-673)
1. How are plane mirrors, concave mirrors and convex mirrors different?
a. Plane mirrors: same size image, formed only backwards
b. Concave mirrors: cave in-look like the inside of a spoon
c. Convex mirrors: pop out-look like the backside of a spoon
2. What is the difference between a mirror and a lens? (How do they interact with light?)
a. Mirrors reflect light and lenses transmit light.
3. Describe the difference between a convex lens and a concave lens.
a. Convex lens-thinker in the middle than at the edges
b. Concave lens-thinner in the middle than at the edges
Chapter 17 Introduction to Electricity (p. 474-486, p. 494-499)
1. How do different charged particles interact?
a. Opposites attract and like charges repel.
2. What is static electricity?
a. Static electricity is electric charge with no path to flow along.
3. Explain the relationship between current and resistance.
a. Current = Voltage / Resistance
4. What are the different parts of a circuit?
a. Power – such as battery
b. Switch- turns it on and off
c. Conductor – to make a pathway for electrons
d. Load – what is being powered
5. Compare and contrast a series and parallel circuit.
a. Series – one path for electrons to flow – if one light bulb goes out, they all turn off
b. Parallel – multiple paths for electrons to flow – if one bulb goes out the rest stay lit.
6. What is the difference between charging by conduction, induction and friction?
a. Conduction – when electrons are transferred from an object to another through direct
contact
b. Induction – electrons are transferred when two things are near each other, NO direct
contact
c. Friction – electrons are transferred through rubbing (balloon on your head makes your
hear stand up)
Chapter 18 Electromagnetism (p. 510 – 520)
1. What is a solenoid?
a. Coil of wire with an electric current running through it
2. What is an electromagnet?
a. A solenoid with an iron core
3. How can you strengthen a solenoid or electromagnet?
a. Add more coils, stronger battery/increase voltage