3 Properties of Linear Motion
A process of changing position relative to some position or object
- tendency of an object to resist a change in motion; must have a force to
- oppose inertia
push or a pull; apply that force to a mass it causes that object to accelerate
spinning motion that takes place when an object rotates about an axis located within an object
motion of an object turning around an axis outside the object (i.e. Earth in its orbit around the Sun)
- A change in motion where there can be an increase or decrease in speed or a change in direction; the rate at which the velocity of an object changes; change in velocity/time
- speed of a car changes from 15 m/s to 25 m/s in 20 secs.
(25-15 m/s)/20 sec = 10/20 = 0.5 m/s2
A change in position over a period of time
A change in position over a period of time and the direction it is traveling in
Define Centripetal Force
Any force that causes an object to follow a circular path
Force that works against motion; one object rubs against another
Force that works against motion; one object rubs against another
Define Air Resistance
Friction with the air; collisions with the invisible air
Described by magnitude (how large it is) only
Need both magnitude and direction
The reluctance of an object to change its state of rotation
3 Controls that Change Velocity
- 1. Acceleration (gas pedal)
- 2. Change in Direction (steering)
- 3. Deceleration (brakes)
Newton’s 3 Laws of Motion
- Law of Inertia: if there is no force on an object then the velocity is constant
- Second Law: the acceleration of a mass is directly proportional to the force and inversely proportional to the mass - F=ma
- Third Law: every force has an equal and opposite force; these two forces act on two different objects at the same time; force always occurs in pairs; used in rocket launches
Inertia Activities - pg. 43 & 44
Demonstrates the concept of inertia, which is the tendency of an object to resist a change in motion; must have a force to oppose inertia
Spinning Egg Puzzle - pg. 45
The insides of the raw egg are more difficult to spin than when cooked. The spinning force is exerted to the shell and not the contents. The coupling between the shell and the liquid is weak. Controlling the shell controls the contents of the cooked egg but not the raw egg. When you stopped the eggs and then let go, the liquid in the raw egg was still moving. This movement started the egg spinning again. If you spin the hard boiled egg hard enough, it will stand on the end converting some of its kinetic energy into potential energy. Research shows that the friction of the egg with the table provides the force required to raise the egg's center of gravity.
Rotational Inertia, Motion Activity - pg. 47
- (roll the 2 cans down the ramp, one with solid contents one with liquid)
- The rotational inertia depends not only upon the mass but also upon the manner in which the mass is distributed about the rotational axis. The gravity pulls down the ramp depends on the mass; therefore it's the distribution of the mass that matters.
Why is force of gravity on the moon less than on Earth?
The moon is smaller than the Earth therefore has less of a gravitational pull
Why do planets end up as balls?
What is gravity?
Gravity is a force.
What does the force of gravity between 2 objects depend on?
- 1) mass of the objects
- 2) distance between the objects
Law of Universal Gravitation
The attractive force between two masses is directly proportional to the product of the masses and inversely proportional to the distance squared.
2m between objects = 2 squared = 4 = 4/1 = 1/4
Center of Gravity
the point at which the mass of the object seems to be concentrated
Center of Mass
the mean location of the gravitational force acting on a body
middle of a uniform object; the balance point
equity of distribution
Why were females able to pick up the chair and males couldn't?
Females have a lower center of gravity because they are smaller in the shoulders and larger in the pelvic area so their center of gravity is nearer the hips.
What is a support base?
The region bounded by body parts in contact with a support surface or surfaces, such as the ground, that exerts a counterforce against the body's applied force. The outline of a foot is the base of support when standing on one leg.
How do you find the center of gravity for irregular shapes?
What is your biological gravity detector?
2 Kinds of Vestibular Organs
- Semicircular canals - 3 structures that detect rotational motion of the head
- Otolith - detects linear motion of the head; contains small sensory areas called macula that contain hair cells (receptors) with sillia on them and are imbedded in the otolith membrane (gelatinous). On top of the membrane are small piles of calcium carbonate that are the actual otoliths, more dense than surrounding area they have greater inertia detecting linear motion when acceleration occurs, sillia bend and sends messages to the brain.
the property of a body that causes it to have weight in a gravitational field; amount of stuff in something
force on an object due to gravity
anything that has mass & volume
the ability to change matter; has to be absorbed or released from the environment
the amount of heat required to raise the temperature of 1 gram of water 1 degree Celsius
Physical vs. Chemical Properties of matter
- Chemical - you can see when substance undergoes a chemical change
- 4 easy ways to know:
- color change
- gas forms, see bubbling and fizzing
- a light
- a gain or a loss of heat that can be recorded
- Physical - can observe or measure, no change in composition
3 States of Matter
- Solid - particles in a fixed position; no freedom to change position; has less energy than the same in liquid form; fixed volume; definite shape
- Liquid - has definite volume and indefinite shape; takes the form or shape of its container
- Gas - particles are in a constant state of motion; speed of particles is temperature dependent - hot faster & cool slower; no shape or volume
6 Changes of the State of Water
- + Heat NRG
- Sublimation - Solid to Gas
- Melting - Solid to Liquid
- Evaporation - Liquid to Gas
- - Heat NRG
- Deposition - Gas to Solid
- Condensation - Gas to Liquid
- Freezing - Liquid to Solid
heat absorbed or radiated during a change of phase at a constant temperature and pressure
Law of Conservation of Mass
Mass cannot be created/destroyed, although it may be rearranged in space, and changed into different types of particles. This implies that for any chemical process in a closed system, the mass of the reactants must equal the mass of the products
Conservation of Mass Activity - pg. 83
When determining whether the mass of an object is affected when it is cut or the shape is changed, and measuring the mass on a scale we find, the law of conservation of mass states that matter is neither created nor destroyed. Objects weigh the same whole, cut up, or shaped differently.
Conservation of Mass Alka-seltzer Activity - pg. 84
When determining what happens to the mass of an alkaseltzer tablet as it dissolves we find that the mass was the same for both the separate and combined parts because mass is always conserved. The states of the parts may change but the mass is fixed. When the lid is put on the jar, it makes a closed system. The gas does not escape so the mass is conserved.
Gas Takes Up Space Activity - pg. 85
(blowing up a balloon with alkaseltzer)
When demonstrating the alkaseltzer and water make a colorless gas, carbon dioxide, and that gases take up space we find that the alkaseltzer dissolves and produces a gal that blows up the balloon.
Properties of Carbon Dioxide Activity - pg. 86
(Heavier than Air, Colorless and Puts out Fires)
When demonstrating that carbon dioxide is colorless, heavier than air and does not support combustion we find that the carbon dioxide extinguished the match because it cannot support combustion. This was proved when the gas was poured into the small cup and the candle went out. As carbon dioxide is poured from one container to another, the level in each container changes. The large container now has less, and the small cup has more carbon dioxide than when we started. The level of gas in each container can be observed by lighting a match and lowering it into the container. Carbon dioxide is heavier than air and can be poured from one container to another. It will not support combustion, the candle will go out when it comes in contact with the gas.
the energy of moving particles
How is heat measured?
Heat energy is measured by calorie
the degree of hotness or coldness of a body or environment corresponding to its molecular activity
How is temperature measured?
Temperature is expressed quantitatively by a number that corresponds to a scale and is measured in degrees.
3 Temperature Scales
- Fahrenheit - 1714
- boiling point 212oF
- freezing point 32oF
- zero point
- Celsius - 1742
- boiling point 100oC
- freezing point 0oC
- Kelvin - 1848
- boiling point 373 K
- freezing point 273 K
3 Ways Heat Energy is Transferred
- Conduction - the transfer of heat energy from one molecule to another by direct contact
- Convection - the transfer of heat energy from one molecule to another by the movement of fluid's circulation in a system
- Radiation - transfer of heat energy by electromagnetic waves; moves through space does not need a substance (i.e. the sun's radiation)
long wave lengths = low frequency and low energy; short wave lengths = high frequency and high energy
2 Properties of Electromagnetic Waves
- ROYGBIV - the colors of the rainbow, visible light
- Speed of Light - the speed at which these waves travel (186,000 miles p/sec)
a substance that readily conducts electricity and heat
a material such as glass or porcelain with negligible electrical or thermal conductivity
the entire frequency range of electromagnetic waves
the process in which there is movement of a substance from an area of high concentration of that substance to an area of lower concentration
the temperature at which a substance will catch fire
chemical reaction where a substance reacts rapidly with O2 and produces heat and light
Boiling Water in a Paper Cup Activity - pg. 104
- Results: The cup will not burn on the bottom where there is water. The top of the cup will still catch fire, but will burn only to water level.
- Conclusion: The cup is kept cool enough by the water to keep it from catching fire, therefore keeping it below it kindling point. The boiling T of water is 212 degrees F, but paper burns at 454 degrees F.
Temperature Scales Activity - pg. 105
Most thermometers depend upon the expansion of a fluid as the temperature increases. The Celsius thermometer has a freezing temperature of 0 degrees Celsius and a boiling point of 100 degrees Celsius. The Fahrenheit thermometer has freezing and boiling points of 32 and 212 degrees. Some thermometers have both scales on the same apparatus.
What is fire?
The process of combustion of inflammable materials producing heat and light.
What 3 things are necessary for a fire?
Fire triangle - fuel, oxygen, and right kindling temperature
Fortune Telling Fish - How does it work?
The fish is mad of cellophane, which reacts to the moisture on your hand not heat.
What is air?
A mixture of gases required for breathing; atmosphere; the stuff that the wind consists of and is held in place by gravity
Properties of Air
- 1. Air takes up space
- - fills in the spaces not taken up by matter
- 2. Air has weight
- 3. Air has pressure
- - the weight of the air above
Composition of Earth's Atmosphere
- 78% Nitrogen
- 21% Oxygen
- 1% Trace Gases
pressure pushes in in all directions on all sides - fluids in a body are pressing outward
a gas in a solid; tiny particles suspended in a gas (i.e. whipping cream, shaving cream, marshmallows)
air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure
What is our air pressure at standard sea level?
14.7 lbs/sq. in. or 10 N per/sq. cm.
What is meant by "thin air"?
Up on a mountain the pressure decreases; the higher you are the fewer gas molecules you'll find
Air flows . . .
from areas of high pressure to areas of lower pressure
Boyle-ing Marshmallows Activity - pg. 81
Results: As you pull down on plunger with your finger over the hole, the marshmallows expand in size. Once your finger is removed the marshmallows will shrink, the air inside the marshmallows escapes and collapse when air pressure is increased again.
What is Boyle's Law?
The volume of a gas is inversely proportional to its pressure when the temperature is held constant.
P1/P2 = V2/V1
What makes the Egg in a Bottle activity work? - pg. 82
- Result: The egg will bob up and down, then slowly descend into the bottle and finally pop into the bottle.
- Conclusion: The bobbing up and down of the egg is from the escaping air. The heat expanded and drove out part of the air trapped inside the bottle. When the paper stops burning, the air within the bottle cools and the inside pressure is reduced. The higher pressure outside forced the egg inside.