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Calendar

Choose the best answer to each question and write the appropriate letter in the space below.

 1)  Where is the center of gravity of a softball bat located?
 A) In the thin handle
 B) Exactly halfway along the bat
 C) In the more massive end of the bat

 2)  When a wrench is slid spinning over a frictionless tabletop, its center of gravity follows __________.
 A) a regular straight-line path.
B
) a straight-line path with irregular speed.

 C) a wobbly path with irregular speed.

 3)  The center of gravity of an object can be located by __________.
A) drawing lines straight down from suspension points.
 B) looking at the intersection of lines drawn from suspension points.
 C) balancing it above your finger.
D
) all of the above will work

 4)  In which of the following is the center of gravity located at a point where there is no mass?
A)  Glass of milk
 B) Cookie
 C) Pineapple
 D) Donut
 E) Apple

 5) An object will fall over if its center of gravity is __________.
 A) too high.
 B) too low.
 C) not over its area of support.
 D) outside the object.

 6) When you carry a heavy load with one arm, why do you tend to hold your free arm away from your body?
 A) To look good
 B) To be ready to grab something in case you fall
 C) To change the mass of your body
 D) To change the weight of your body and the load
 E) To change the center of gravity of your body and the load

 7) If an object is in unstable equilibrium, any displacement will __________.
 A) raise its center of gravity.
 B) lower its center of gravity.
 C) neither raise nor lower its center of gravity.
 D) increase its mass.
 E) decrease its mass.

 8) If an object is in stable equilibrium, any displacement will __________.
A) raise its center of gravity.
 B) lower its center of gravity.
 C) neither raise nor lower its center of gravity.
 D) increase its mass.
 E) decrease its mass.

 9) If an object is in neutral equilibrium, any displacement will __________.
 A) raise its center of gravity.
 B) lower its center of gravity.
 C) neither raise nor lower its center of gravity.
 D) increase its mass.
 E) decrease its mass.

 10) If you try to touch your toes while standing flat against a wall, you probably will fall over. The reason this happens is that __________.
 A) your center of gravity is outside your support area.
 B) your center of gravity is not located directly above your support area.
 C) both A and B 

11) The center of mass of the solar system __________.
 A) is at the center of the sun.
 B) varies as the planets move.
 C) neither A nor B

 12) The long heavy tail of a spider monkey enables the monkey to easily vary its __________.
 A) weight.
 B) momentum.
 C) inertia.
 D) center of gravity.
 E) none of the above

 13) The center of mass of a human body is located at a point __________.
 A) that is fixed, though different for different people.
 B) that is always directly behind the belly button.
 C) that changes as a person bends over.
 D) none of the above

 14) An object thrown into the air rotates about its __________.
 A) midpoint.
 B) edge.
 C) center of gravity.
 D) geometric center.
 E) none of the above

 15) If a plumb line is dropped from a suspension point of a rectangular sheet of plywood __________.
 A) half the mass of the wood will be on either side of the line.
 B) half the weight will be on either side of the line.
 C) the line will pass through the center of gravity of the wood.
 D) all of the above
 E) none of the above

 16) A fish suspended in water is in what kind of equilibrium?
 A) Stable
 B) Unstable
 C) Neutral 

17) A ball resting on the floor is in what kind of equilibrium? 
A)
Stable
 B) Unstable
 C) Neutral 

18) A picture hangs on a wall by a wire that is passed over a supporting nail. The picture is in stable equilibrium because __________.
 A) any slight push will raise its center of gravity.
 B) after any small push, it will return to its original position.
 C) its center of gravity is directly below the supporting nail.
 D) all of the above

 19) Based on stability concepts, you would expect a very broad tree to have __________.
 A) a very broad root system.
 B) very deep roots.
 C) exceptionally strong roots.

 20) You push a table tennis ball beneath the surface of water in a glass of water. The center of gravity of the glass of water __________. 
A)
rises.
 B) falls.
 C) neither rises nor falls.

 Write True or False in the space provided.

21) The point located at the geometric center of an object is called the object's center of gravity.
 22) The point located at the center of an object's mass distribution is called the object's center of gravity.
 23) When an object is balanced so that a displacement raises its center of gravity, the object is said to be in neutral equilibrium.
24) When an object is balanced so that a displacement lowers its center of gravity, the object is said to be in stable equilibrium.
 25) When an object is balanced so that a displacement neither raises nor lowers its center of gravity, the object is said to be in neutral equilibrium.
 26) Because the sun has several planets orbiting it, it actually wobbles as it moves through space.
 27) Even though a baseball bat spins and wobbles when thrown in the air, its center of gravity follows a smooth parabolic path.
 28) The center of mass of an object is always located at the object's geometric center.
 29) An unaided object will topple over when its center of gravity extends beyond its support base.

 On a separate sheet of paper, answer the following questions.

30) In terms of center of gravity, discuss what determines whether or not an object will fall over when tilted. Give examples.

31) In terms of center of gravity, discuss the three types of stability. Give examples of each type.

32) Discuss the role of center of gravity when a high jumper executes a "Fosbury flop."


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