Force -a push or a pull F = ma
Speed Constant speed -describes how fast an object moves -an object that travels equal distances in equal amounts of time Speed = distance/ time Distance = speed x time Time = distance/speed
Momentum -property of a moving object that depends on its mass and velocity Momentum = mass x velocity M = mv Momentum explains the power behind a baseball after a hard hit by a bat. It also explains the power of a speeding bullet. A bullet is small and light, but its extreme velocity gives its deadly momentum. Their low speed combines with their enormous mass to give them tremendous momentum
Acceleration -change in velocity -an increase or decrease in speed or a change in direction
Mass – the amount of matter an object contains Weight – the force due to gravity on an object
Newton’s first law Inertia An object at rest remains at rest and an object in motion maintains its velocity unless it experiences an unbalanced force Ex: Carefully place that hockey puck on the air hockey table so it is completely still. Newton’s first law dictates that the puck will remain still, unless some force comes along to set it into motion. Inertia Means resistance to change in the state of motion Ex: the need for seat belts Did you ever ride in a car that came to a sudden halt? Your own inertia kept you moving forward. Inertia also explains the trouble you might have in pushing a stalled car. If you ever tried this, you know the toughest part is at the beginning when you apply the force to set the car into motion. Once the car is moving, it is easier to keep it moving.
Newton’s second law F = ma
Newton’s third law For every action force, there is an equal and opposite reaction force
Interference Constructive interference Destructive interference -occurs when several waves in the same location combine to create a single new wave with different characteristics Constructive interference -one new wave has an amplitude that is the sum of the amplitudes of the two separate waves Destructive interference -occurs when the crest of one wave meets with the trough of another
Polarization
Reflected – when light bounces back from an object Law of reflection- States that the angle of incidence is equal to the angle of reflection Incidence is the falling of a wave on a surface
Refraction – the bending of waves when they pass from one medium to another
Resonance
Potential energy
Kinetic energy
Gravitational potential energy – energy that results from the gravitational attraction between objects Gravitational PE = mgh m = mass g = acceleration h = height
Elastic potential energy
Mechanical energy -the total gravitational potential energy, elastic potential energy, and kinetic energy of an object make up its mechanical energy
Law of conservation of energy -energy cannot be created or destroyed
Specific heat – the amount of energy required to raise the temperature of 1 kg of a substance by 1 degrees celsisus
Convection – is a way heat moves through a system by the movement of the heated substance itself. It occurs in substances that can flow – liquids and gases – but not in solids
Conduction – transfer of heat energy between particles in direct contact; the particles can be within the same object or within two objects that are in direct contact and at unequal temperatures Conductor – a material through which energy can easily be transferred as heat Insulators – materials that are poor conductors
Electromagnetic waves Gamma rays, x rays, ultraviolet rays, infrared rays, microwaves, and radio waves Radiation Energy transferred as electromagnetic waves. Only type of energy that can transfer across empty space – no physical contact is required
Electric circuit -the path that charges follow when they are flowing in a current Open circuit -no charge can flow, turns off light, etc Closed circuit -charge is flowing, turns on light, etc Resistors -special conductors wired into circuits to control the current Series circuit -a single pathway exists for the charge to flow Parallel circuit -provides more than one path for charges to follow to complete the circuit