Matter: Pressure

The net force on your reclining body is around

A. 6000 pounds.

B. 600 pounds.

C. 60 pounds.

D. 6 pounds.

E. 0 pounds.

Magdeburg Spheres 1654 Otto von Guericke

Gaspar Schott

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Energy and Matter

• Net Force – agent of change, producer of motion.

• Energy - measure of change.

• Energy is conserved.

• Mass is conserved.

• Mass/Energy is conserved. Energy and Mass are different manifestations of the same underlying quantity.

Conservation of Energy

Richard FeynmannNobel Laureate

V = 0

Net Force

Force Picture: Newton’s Laws

V increases because a net force acts down the incline in the direction of motiongravityincline

Kinetic energy = 0

Energy Picture

V increases because gravitational potential energy is transformed into kinetic energy

Stored or gravitational potential energy because of height above bottom of incline

Marble/Cup Experiment 1

half cup half cup

Marbles released at same height for two different angles of incline.

books books

Trial 1 Trial 2 X

Measure how far the cup goes. If it tilts, measure to the red x.

How do the distances compare?

ruler

ruler

Questions• What kind of energy does the marble have at the top of

the incline before it is released?• What kind of energy is it transformed to at the bottom of

the incline just before it hits the cup?• What happened to the energy the marble had at the

bottom of the incline? Look at page 272 in your book.

In the simple case of a constant force along the motion, work is just the force multiplied by the distance traveled. The marble exerts a force on the cup while they collide. The marble’s kinetic energy of motion is turned into work on the cup as they move together. The cup and marble come to a stop. The work generates heat energy through friction. All that is left in the end is heat in the table surface and cup – the worst form of energy because you can’t get it all back. The gravitational potential energy was transformed into heat.

WORK IS TRANSFER OF ENERGY.

Marble/Cup Experiment 2

half cup

Marbles released at different heights: one height twice the other.

books

Trial 1

Trial 2

X

Measure how far the cup goes. If it tilts, measure to the red x.

How do the distances compare?

ruler

Questions

• Which marble has more gravitational potential energy?

• How does the gravitational potential energy depend on height?

The greater the height the greater the gravitational potential energy. This is a linear relation or direct proportion. You can use this in pre algebra to teach the pattern of a linear or straight line graph.

1 123

How can one monkey hold up three?

11

23

Resistance = 3 units

Effort = 1 unit

1 x 3 = 3 x 1

1 123

Effort x distance from fulcrum = Resistance x distance from fulcrum

Force on resistance

= 3 units

Force of effort = 1 unit

Work = Force along motion times distance

Work of effort = 1 x small side of yellow triangle

Work on resistance = 3 x small side of red triangle

Work of effort = Work on resistance (energy is conserved)

By similar triangles the small side of the yellow triangle is three times the small side of the red triangle.

Energy: Orbit of the Eartharound the Sun

p. 278 of your text: “No force is needed to keep it [the Earth] moving, but gravity forces its change of direction.”

It depends on the meaning you have of moving. If moving means speed, then it is correct. If moving means path followed, then it isn’t correct.

Energy: Orbit of the Eartharound the Sun

p. 278 of your text: “It acquired its position and motion when it was formed.”

Squeak Simulation

Matter: Atomsp. 282 of your text: “…scientists have come

to believe electrons are more like bees buzzing around in a hive.” It’s more like bees “fuzzing” around.

A two-layer scanning tunneling microscope (STM) image of the surface of a BSCCO (bismuth, strontium, calcium, copper and oxygen) high-temperature superconductor. Electron cloud. These simulated images are rotating so you can see what

they look like in 3D. They are different energy states of an electron in hydrogen atom.

If the nucleus of an atom were about the size of a baseball, the electron clouds would be about the size of the Huston Astrodome. Everything is mostly empty space. Let the force be with you.

Matter: Atoms

Matter: Atomsp. 284 of your text: “There are currently 109 known elements.

We are up to element 118 now with a recent (June 2005) Livermore / Dubna discovery. The Livermore / Dubna collaboration has created elements 113, 114, 115, 116, and 118. Element 117 has not yet been created.

Matter: Scale