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.

Newton's First Law

The following link describes Newton's first law when applied to aircraft.

http://www.grc.nasa.gov/WWW/K-12/airplane/newton1.html

Shoot the Monkey

1. I fired the cannon at a 30 degree angle with an initial velocity of 30 m/s to get the monkey to catch the banana in mid-air.


2. To get a successfull shot you must predict where the monkey will be seconds after the shot is fired. You need to aim where the monkey will be.

As long at the cannon is pointed at the monkey or below him, he will most likely catch the banana because gravity is acting on both the banana and the monkey at -9.8m/s.

Applied Science

http://www.sciencedaily.com/releases/2007/09/070911202513.htm

This article is about using science in the medical field for artificial respiration. It looks at the body's ability to adapt to recurring stimuli. New respirators are being developed with this newly aquired information that could minimize the need for sedation or paralysis currently necessary for some patients on mechanical ventilation.

Velocity vs. Acceleration

Velocity is the rate and direction of the change in the position of an object.
ie. A car going down a curvy road at 50 mph experiences a chaning velocity as it goes from one turn to the next.



Acceleration is is the rate of change of velocity with time.
ie. A car only experiences acceleration when it starts moving from a stop. The same car going down the curvy road at a constant speed of 50 mph experiences no change in acceleration.

Scientific Method

These are the steps in the Scientific Method

1. Recognize a problem
2. Make an educated hypothesis about the answer
3. predict the consequences of the hypothesis.
4. Preform experiments to test prediction.
5. formulate the simplest general rule that organizes the three main ingredients: Hypothesis, prediction, and experimental outcome.