What is Physics?

• Physics is the study of matter and energy

Physics has many subcategories:

Mechanics- the study of motionDynamics- the study of causes of motion

Thermodynamics- heat behaviors

Waves, Sound, Light, OpticsModern Physics- nuclear physics, relativity, astrophysics, etc.

Physics is a science an exploration into how things work and why

Making connections in science-- modeling and the scientific method

A model is an analogy or comparison to a familiar idea, e.g. comparing light waves to water wavesThe Scientific Method is a problem solving procedure:

Observation of a natural phenomenaHypothesis-- an educated guessExperimentation leads to Theory

Wider experimentation leads to dismissal or acceptance as Law

- descriptive, not restrictive

Physics--> the study of matter and energy

Energy-- the ability to do work Which is

anything!

Pure Energy:Sound, Light,

Heat

Matter: Described by its

specific properties

Energy-the capacity to do work

• Potential Energy• -gravitational• -elastic• -chemical• -etc.

• Kinetic Energy• the energy contained

by any object that is in “motion”

• unless otherwise specified, the surface of the earth is considered stationary

(Some) Properties of Matter

Mass: How much stuff - quantity of matter

Inertia: A resistance to a change in motion

Volume: How much space the matter takes up

Mass Density: the ratio of mass to volume

D =m

Vunits: g/cm3

D =m

V

This is one physical concept represented mathematically, but it is three equations:

m = DVV =

m

D

For our purposes, these are all the same base relationship for use in problem solving.

Problem Solving ProcedureRead through the entire problem!List the given information (quantity

with number and units).Find and write a base equation for the

given information.Put the numbers in and solve.Circle your final answer with correct

units!

What is the density of a rectangular object that has a mass of 63.2 g and is 3.42 cm long, 1.09

cm wide and 2.56 cm in height?

m = 63.2 gl = 3.42 cm

w = 1.09 cmh = 2.56 cm

D = ? D = m

VV = l• w • h

D = m

l• w • h

= 63.2 g

(3.42 cm)(1.09 cm)(2.56 cm)

= 6.62 g/cm3

The mass of a block of wood is measured to be 125.25 g. The length of the block is measured as 5.25 cm, the width is measured as 6.80 cm and the height is measured as 8.35 cm. Find the mass density of this wood block.

The density of a sample of lead is found to be 11.6 g/cm3. If the mass of the lead is measured to be 125.0 g, what must be the volume of the sample?

A block of wood with dimensions of 5.35 cm, 3.45 cm and 2.45 cm has a mass density of .876 g/cm3. What must the mass of that block be?

.420 g/cm3

39.6 g

A wooden block of mass 115.62 g has a density of .687 g/cm3. What must the height of the block be if the length is 12.35 cm and the width is 8.25 cm?

A block of unknown material is found to have a mass of 245 g and dimensions of 22.0 cm, 15.0 cm, and 12.0 cm. Will this block float in water?

What is the mass of a block of wood that has a density of .760 g/cm3 and measures 15.0 cm by 14.0 cm by 8.35 cm?

Oh yes!

Explain how someone may have used the scientific method in order to solve a problem. Explain by outlining and giving examples following each step of the method. This example can be a scientist, such as Copernicus, or simply an example from every day life.