3-4 Physics Notes Slides 1 to 19 · PDF filePhysics Unit: Force & Motion ... 5. CHEMICAL...
Transcript of 3-4 Physics Notes Slides 1 to 19 · PDF filePhysics Unit: Force & Motion ... 5. CHEMICAL...
Physics Unit: Force & Motion What is physical science?
A. Physical science is a field of science that studies matter and energy. B. Physical science has 2 main branches:
1. PHYSICS: the study of how matter and energy interact • robotics, nuclear energy, solar
panels 2. CHEMISTRY: the study of the
structure, makeup, and changes of matter • chemicals, acids & bases,
medicines
What is energy? A. ENERGY: the ability to do work or
make something happen B. All forms of energy fall under two
categories: 1. POTENTIAL ENERGY: stored
energy that could make something happen a. Chemical Energy b. Nuclear Energy c. Stored Mechanical Energy d. Gravitational Energy
2. KINETIC ENERGY: used energy that is making something happen a. Radiant Energy b. Thermal Energy c. Motion d. Electrical Energy e. Sound
What are the different forms of energy?
A. There are many different forms of energy to make things happen.
B. Below are 6 of the major forms: 1. MECHANICAL ENERGY: the
energy in moving objects 2. ELECTRICAL ENERGY: energy
from the flow of electrons 3. ELECTROMAGNETIC ENERGY:
energy in the form electrical and magnetic waves that can travel through space
4. HEAT ENERGY: thermal energy that comes from moving particles of matter (friction)
5. CHEMICAL ENERGY: energy that holds particles of matter together (chemical bonds)
6. NUCLEAR ENERGY: energy stored in an atom’s nucleus
What is a wave? A. WAVE: a disturbance that transports
energy from one place to another. 1. A wave is energy that travels over a
distance. 2. There are two major forms of waves:
a. MECHANICAL WAVES: waves that travel through matter like air or water
b. ELECTROMAGNETIC WAVES: waves that can travel through matter or empty space
What is a wave? B. Waves that travel through matter can do it one of two ways:
1. TRANSVERSE WAVE: waves that move up and down a. There are two parts to a transverse wave
i. CREST: the highest point of a wave ii. TROUGH: the lowest point of a wave
2. LONGITUDINAL WAVE: waves that move back and forth a. There are two parts to a longitudinal wave
i. COMPRESSION: where the particles are close together ii. RAREFACTION: where particles are far apart
What is mechanical energy? A. MECHANICAL ENERGY: the
energy an object has that causes it to move
B. Mechanical energy can come in one of two ways: 1. STORED MECHANICAL ENERGY:
potential mechanical energy that could cause an object to move
2. MOTION: kinetic mechanical energy that causes an object to move
C. A force acting on an object is required for mechanical energy
What is a Force? A. FORCE: a push or pull exerted on an object B. To describe a force, you must know a force’s size and
direction C. Size and direction can cause one of two situations:
1. BALANCED FORCES: forces on an object equal in size but opposite in direction
2. UNBALANCED FORCES: forces on an object that are no longer balanced, causing a change in the motion of an object
What is a Force? D. Forces are drawn as arrows of different sizes.
1. Arrows show direction 2. Different sizes show how strong the force is
E. Forces are measured using instruments: 1. A spring scale is used to measure a force using Newtons 2. NEWTON: a standard unit of force depicted as an N
3 N 3 N 10 N 1 N
8 N
3 N
Which major forces affect the motion of objects? A. Gravity is one of the major forces
acting on objects 1. GRAVITY: a force of attraction
between all objects in the universe
B. On Earth, objects are pulled to the center of the planet by the dense mass of the planet’s core
C. Friction is another major force moving objects must contend with: 1. FRICTION: a force that pushes
back on a moving object 2. This force often occurs when an
object rubs against, moves over or through another type of matter
3. Friction can cause heat as a result of rubbing
What is Magnetism? A. MAGNETISM: the force (push or pull)
produced by magnetic materials B. MAGNET: a material that pulls or
attracts the metals iron, cobalt, and nickel 1. All magnets have two common
properties: a. MAGNETIC POLES: two
places on a magnet where the forces are the strongest i. The two poles are marked
North (N) and South (S) ii. Opposite poles are attracted to
each other iii. Similar Poles repel each other
b. MAGNETIC FIELD: the space around a magnet where the force acts on other objects
What is Magnetism? C. Permanent magnets can cause iron, cobalt, or nickel to
become temporary magnets. 1. Each atom in an object as positive and negative end 2. When metals are pulled on by a magnetic field, these ends
line up, with positive being attracted to negative. 3. This lining up creates a magnetic field around the metal
How is motion described? A. Motion can be described in terms of speed and
direction: 1. VELOCITY: the speed and direction of a moving
object a. Two things must be measured to determine
speed i. Distance in meters (m) ii. Time in seconds (s)
b. Direction must be figured out using a compass to determine north, south, east or west.
c. Velocity can be written as a formula: i. Distance ÷ Time = Speed & Direction ii. m ÷ s = m/s & Direction
What is Work? A. WORK: force exerted on an object that moves it over
a measurable distance 1. Two things must be measured to determine work:
a. Force in newtons (N) b. Distance in meters (m)
2. If an object does not move, no work is accomplished.
B. Work can be written as an formula: 1. Force x Distance = Work 2. N x m = J 3. Work is written in Joules (J)
a. JOULE: a unit of work equal to a force of 1 N that moves an object 1 m.
What is a Simple Machine?
A. MACHINE: a device that makes work easier 1. A machine can make work easier in three ways:
a. Reducing the size of the effort force b. Changing the direction of the effort force c. Changing the speed at which work is done
2. Most machines are a combination of two or more simple machines: a. Wheel and Axle b. Lever c. Inclined Plane
How do Levers Work? A. LEVER: a bar or plane that is free to pivot or turn around a fixed
point 1. Two major parts of a lever:
a. FULCRUM: the fixed point a lever pivots or turns around b. ARM: the bar or plane pivoting over the fulcrum
B. A lever does two things to make work easier: 1. Reduce the size of the force 2. Changes the direction of the force
How do Wheels & Axles Work? A. WHEEL & AXLE: a circular object that turns around a fix point
or rod 1. It reduces the friction between weight and the surface it moves
over. 2. The longer the diameter the further the distance the wheel will
move.
How do Wheels and Axles Work? B. Wheel & axles are parts of other simple machines:
1. Pulleys are a wheel and axle with a rope wrapped around it 2. Gears are special wheels with teeth able to bite and turn each
other.
How Do Inclined Planes Work? A. INCLINED PLANES: a slanted surface or ramp
1. An inclined plane makes work easier by changing the angle you have to exert a force to lift an object.
2. The lesser the angle of an inclined plane, less force needs to be exerted.
How Do Inclined Planes Work? B. Inclined planes are parts of other simple machines:
1. A wedge is two planes back to back 2. A screw is an inclined plane wrapped around a cylinder.