Little Shop of Physics

I did the "Rubber Pencil" experiment. It was quite entertaining. A good way to pass time when you are board.

According to the site this is what happens.
"The monitor redraws the screen from top to bottom at a rate near 60 Hz. This means that it will act like a strobe light, and allow you to "stop" fast motion. But since it is drawn from top to bottom, it will stop the motion at different points! So it will look like the pencil has curved: the top will be stopped at one time, and the bottom at another time!"

This makes sense and I found that it also works not in front of the computer screen, just not quite as well but still entertaining none the less.

Tides and Gravity Labs

Critical Speed Lab
1) the earth needs to be traveling at 29,500m/s to successfully travels around the earth.
2) The earth will fly off tangent to the sun if the earth's speed is greater than critical speed
3) The earth will crash into the sun if its speed is less then critical speed
4) The planet closest to the sun will travel faster than the planet furthest away from the sun.
5) Venus's critical speed would be greater than Mars's.
6) A and C are connected and have the same speed.
7) The spaceship would be sucked into the neutron star because of its massive amouts of gravity.
8) Gravity holds the earth together.














Gravitational Force Lab
1) Point A has a greater gravitational effect on the moon because it closer to the moon.














2) Because the distance is shorter between the moon and the Earth.
3) Because the earth has a high tangential speed so it is falling around the sun.
4) r because gravitational attraction is directly related to teh distance between the two objects.
5) a Increase
b Increase
6) a Decrease
b Decrease
7) Point A

Tidal Force Lab
1) The Earth and the sun have the largest gravitational force.
2) The Earth and the moon have the largest tidal force.
3) For tidal effect, two objects located close together is more important than the strength of gravitational force.

Torque Project

Here is the powerpoint explaining our science project.

PowerPoint Presentation

Torque is defined as force multiplied by the distance from the fulcrum.

Finding Center of Gravity

Date: 12/19/07

Purpose: To find the center of gravity of a pencil

Equipment: Pencil, and Triangular prism to use as your fulcrum point


Procedure:

1. Step # 1 – Place the pencil on the fulcrum.
2. Step # 2 – Move the pencil about the fulcrum until it balances without you touching it.


Conclusion: When the pencil is balanced on the fulcrum, You have found its center of gravity.

Potential Energy Gizmo

Calculationg Gravitational Potential Energy
1. a) The potential energy of the ball on the ground is 0J.
b) The potential energy of the paper is .31J.
c) If the paper is raised, its PE increases. If the paper is lowered, its PE decreases.
d) Horizontial movement has no affect on the PE of the paper.
e) The PE of the paperclips at the 2m shelf is .78J. The PE of the clips doubles at the 4m shelf to 1.57J.
f) I would expect the PE of the paperclips to be cut in half when they are lowered from the 2m shelf to the 1m shelf. Its PE is .39J at the 1m shelf.

2. a) PE of Ball: 1.96J Paperclips: 0.78J Paper: 0.16J
b) The ball has the greatest mass. The wad of paper has the smallest mass. The larger the PE the larger the mass.
c) The GPE is equal to mass times acceleration due to gravity (9.8 m/s) The Balls GPE is (1.96)=m(9.8)(2)) --> m=0.1g; The mass of the paperclips is (.78)=m(9.8)(2)) --> m=0.04g; The mass of the wad of paper is (0.16)=m(9.8)(2) --> m=0.009g
d) The PE of the clips is 1.96J at the 5m shelf; The PE of the wad of paper at the 3m shelf is 0.24J.


1. Ball Placed at the 1m Shelf
a) PE= 0.98J
b) PE at 4m = 3.92J
c) the PE quadrupled

2. Paperclips on the 5m shelf.
a)PE=1.96
b)PE at 3m =1.18
c) there are no other forces other than gravity acting on the paperclips. It is nagative because you are going from a higher level to a lower level.

3. Paper on the 2m Shelf
a)PE=0.16
b)PE=0.16
c)Net change of the paper is Zero. No work is being done by non-gravitational forces.

Physics Answers

From questions on http://www.glenbrook.k12.il.us/GBSSCI/PHYS/CLASS/newtlaws/u2l4a.html

1. The fore is equal on both the firefly and the bus.

2. D) Rockets do accelerate in space because they push on the expanding gas.

3. C) the same size as the acceleration of the bullet.

4. C) the force is the same in each case.

Spring Gizmo

This Gizmo found the force exerted on the spring and how much it streches on varying strengths of springs when you put different weights on them.

Test on Spring One

I found that spring one was the weakest spring avalible, and would strech the most when weight was placed on the pan attached to the end of the spring.

Test on Spring Three

I found that spring three was stronger than was stronger than the other springs tested. Meaning it streched lass when weight was placed on the pan attached to the end of the spring. You could also use the line of best fit (as shown in picture) to predict other weights and the amout of stretch on the spring.

I observed that the higher tention springs will stretch less when weight is placed on them.