1. Brooke Young Brandon Mock Javier Aranguren
Center of Gravity
Brooke Young
Brandon Mock
Javier Aranguren

2. Major concepts
The centre of gravity is the centre of an object's weight distribution, not necessarily the geometrical centre. centre of gravity is also the centre of mass. the centre of gravity of a uniform object is usually the midpoint of the object. the centre must be above the area of support elsewise the object will topple.a balanced object that any displacement lowers its centre of gravity is an unstable equilibrium, displacment which raises the centre is stable.

3. Historical Perspective
The concept of centre of gravity was introduced by Archimedes, an ancient greek mathematician. Archimedes showed that the torque exerted on a lever by weights resting at various points along the lever is the same as what it would be if all of the weights were moved to a single point, their centre of mass

4. Application of Concepts
to stand on your hands youll have to have the centre of gravity about the area of support from your hands
to balance a pencil you place it oon the eraser to have the centre above the area of support.

5. Think and Explain
1. to balance automobile wheels, particularly when tires are worn unevenly, lead weights are fastened to their edges. where should the cg of the balanced wheel be located?
the cg would be i the middle so it would be balanced
2. why does a washing machine vibrate violently if the clothes are not evenly distributed in the tub?
the cg of the tub is not centred
3. why do we speak of the cetre of mass of the sun, rather than the centre of gravity of the sun?
centre of gravity of the sun is outside of it due the gravitational pull of the planets

6. 4. which glass in figure d is unstable and will topple?
the filled glass would topple for the cg would be outside support area due to raised cg of the liqiud
5. which balancing act in figure E is in stable equilibrium? in stable equilibrium? Nearly at neutral equili brium?
the man with monkey is unstable, the guy crawling his nearly at neutral and bicycle one is stable
6. how can the three bricks in figure f be stacked so that the top brick has maximum horizontal overhang above the bottom brick?

7. 7. why don’t tall floating icebergs simply tip over?
cg of the iceberg lies below the surface of the water
8. in terms of cg, why is work required to push a tabletenis ball beneath the surface of the water?
changes the position of the cg
9. why does a pregnant woman during the late stages of pregnancy or a man with a large paunch tend to lean back ward when walking?
the cg is more forward to they have to bring the cg back above the support area

8. 10. try the following with a group of males and females
10. try the following with a group of males and females. stand exactly two footlengths away from a wall. bend over with a straight back and let your head lean against the wall as shown in figure g. then lift a chair beneath you while your head is still leaned against the wall. with the chair in liftewd position, attempt to staraighten up. give two reason why females can generally do this and males cannot.
females cg is lower due to larger pelvic regions and slimmer shoulders. while mmens are near their chest. mens then cg is outside of their body, outside of support area.

9. Review 1. why is the cg of a baseball bat not at its midpoint?
irregular shape
2. wht part of an object follows a smooth path when the object is made to spin through the air or across a flat smooth surface?
centre of gravity
3. describethe motion of the cg of a projectile, before and after it explodes in mid-air.

10. 4. when is the cg and centre of mass of an object the same
4. when is the cg and centre of mass of an object the same. when are they different?
Same while gravitational force is uniform, differ when not
5. what is suggested by a star that wobbles?
centre of gravity is not palced in the star
6. how can the cg of an irregularly shaped object be determined?
straight under point of suspension
7. cite an example of an object that has cg where no physical material exists?
boomerang

11. Background
The center of gravity of an object is the center of all gravitational force acting upon the object. It is the same as the center of mass, except when the object is large enough to have differences in gravity throughout it. An object can only rest on a base if the object’s center of gravity is between the edges of the base, whether above or below it.

12. Question
What will the center of gravity be on an unused pencil? Will the eraser's mass effect where the center of gravity will be?

13. General Statement
We will conduct this experiment by using a pencil and a table to perfectly balance it to find the exact center of gravity among the pencil.

14. Materials
1. A pencil
2. A marker
3.A ruler
4. A table

15. Procedure
First we will try to balance the pencil perfectly so a portion of it is hanging over the edge of a table. The purpose is to find the exact point where the pencil can hang off the table without falling. Once you have found that point draw a line on the pencil where the pencil begins to hang off the edge. Then measure the distance from the line each direction. Compare the difference and analyze the difference, if any.

16. Safety
The only safety precaution for the experiment is to not get stabbed by the pencil.

17. Table/Graph _________________Pencil Length of pencil - 7.5 cm
Center of gravity cm
(1.25 cm from center)

18. Analysis
After conducting the experiment we found the length from the center of gravity was 1.25 cm longer towards the opposite direction of the eraser. This would be because the metal part and eraser weigh more than the opposite end of the pencil. The metal and eraser helps hold the pencil down, so even though the pencil was not perfectly cut in half, it was cut in half by weight.

19. Conclusion
If we were to cut the pencil in half directly where we drew our center of gravity line, the two halfs would be perfectly even in weight. If we were to flip aroung the pencil so the heavy side was out we would move the pencil 1.25 cm back to the middle, then another 1.25 cm to compensate the weight difference.

20. Evaluation
We found after the experiment the pencil was not evenly "cut in half" for the center of gravity. We found more of the pencil was hanging off the edge than on the table. This is because the metal part around the eraser and the eraser itself carry more weight. So if we were to cut the pencil right where the center of gravity line we drew, they would weigh the same. Even though the two lengths are not the same, the mass is making the center of gravity appear uneven.