physics topics i. mechanicsmechanics ii. waves and opticswaves and optics iii. electricity and...

Physics Topics

• I.  MECHANICS

• II.  WAVES AND OPTICS

• III. ELECTRICITY AND MAGNETISM

• IV. MODERN PHYSICS

• V. ASTRONOMY

Thinking Back…

• What were some of the tools of a Physicist?

Thinking Back…

• What were some of the tools of a Physicist?

Practice safety & ethicsIdentify & describe equipment

Use SI SystemManipulate formulas

The Scientific MethodUse Lab Report Format

What do you know?

• What is a frame of reference?

What do you know?

• What is a frame of reference?

• A system to determine location or motion of an object.

• How can I tell if something is moving and how fast?

What is acceleration?

What is acceleration?

• Rate of change of speed

• Occurs when we fall or go around a corner

What are forces and how do they commonly occur?

What are forces and how do they commonly occur?

• A force is a push or a pull

• They commonly occur in pairs

What are Newton’s Laws of Motion?

What are Newton’s Laws of Motion?

• #1 Inertia

• #2 F = ma

• #3 Action/Reaction

Motion I

Motion in One Dimension - Quantities, Units, Speed, Position, Distance, Displacement, Velocity,

Vector, Scalar, etc. 

Assignment

• Read Chapter 2

• After reading the chapter, complete your Reflections on the chapter.

What you need to know

¤ Motion can be described and analyzed in several ways

¤ How coordinate systems can be used in motion studies

¤ Terms such as displacement, magnitude, vectors

¤ More Terms: scalars, resultant vectors

¤ Interpret motion graphs

¤ Attributes of coordinate system - origin & axis

¤ Models of motion diagrams

Also Needed to Know

¤ Speed, distance (d), and time are scalar quantities.

¤ Velocity, displacement (s), force and acceleration are vectors.

¤ The slope of the distance-time graph is velocity.

¤ The slope of the velocity-time graph is acceleration.

possibilities

• Object not moving, v = 0 m/s

• Object moving at constant velocity

• Object accelerating

• Object decelerating (negative acceleration)

• (Last 2 situations have unbalanced forces acting on them - to be discussed later in the book)

Organizing your thoughts (and units)

• Fundamental Quantities– Length– Mass– Time

• Derived Quantities– Velocity– Density– Volume

• Fundamental Units

– Meter– Kg– Sec

• Derived Units– m/s– g/ml or g/cm3

– m3 or cm3

The "Big Five" Kinematics Equations

Constant acceleration is

assumed

Average Speed/Velocity Defined

v = d / t = ½(Vf + Vo)

Average Acceleration Defined a = ∆v / ∆t = (Vf - Vo) / (tf - to)

Final Velocity of an Accelerating Body

Vf = Vo + a(∆t)

Distance Traveled by an Accelerating Body

d = Vo(∆t) + ½ a(∆t)2

What can I do if I don't know the time interval?

Vf2 - Vo

2 = 2 a d

In the above formulas, a can be replaced with g

g = 9.8 m/s (acceleration on Earth due to gravity when an

object is falling)

Equation of motion for average velocity:

d = vt + di

Online Notes

• http://www.physicsclassroom.com/Default2.html

• This site has information which may be helpful to you in your basic study of Physics.

Scalars & Vectors

• Scalars have magnitude only (a number with units) such as a length of 5.0 m or a speed of 29.3 m/s

• Vectors have magnitude and direction– Velocity: 29.3 m/s North– Force: 25 newtons South– Displacement

Vectors

• Are represented by an arrow

• Length drawn to a chosen scale (1cm:50m/s)

• Direction N S E W

• Vector addition:– Same direction: add– Opposite directions: subtract

Adding Vectors

A

B

R

A

B

R

A + (-B) RA + B R