Question

Center of mass is always at the geometric center.

Question 1 options:

	True
	False

Question 2

Where is the center of mass of a high jumper as they jump over the bar?

Question 2 options:

	Just below the jumpers bellybutton
	Below the bar
	Above the bar
	At the level of the bar

Question 3

If a hammer is thrown in the air…

Question 3 options:

	It will rotate around its center of mass.
	The center of mass will follow a parabolic trajectory.
	The center of mass will change through the flight.
	Both A and B.
	All of the above.

Question 4

The center of mass must be located at a physical point on the object.

Question 4 options:

	True
	False

Question 5

Where is the center of mass on a hula-hoop?

Question 5 options:

	In the center of the hula-hoop, where there is no mass
	Assuming the hula-hoop is symmetrical, the center of mass can be on any point on the hoop
	The center of mass constantly changes based on where the hoop is
	There is no center of mass on a hula-hoop

Answer 1

Q1. Center of mass is always at the geometric center.

Answer: False

Exp: only for simple rigid objects with uniform density, the center of mass is located at the geometrical centre. geometrical centre of a plane figure or an object, it divides the shape into regions of equal moments.sometimes the center of mass doesn't fall anywhere on the object. the center of mass of a ring for example is located at its center, where there isn't any material.

Q2. Where is the center of mass of a high jumper as they jump over the bar?
  
Answer: Below the bar

Exp: when the athlete starts running, the center of mass lies within the body. when he loses his contact with the ground, there is an instantaneous absence of external forces and thus center of mass keeps on travelling in same horizontal path even though athlete gains height. on the bar athlete arch their bodies and that moment their center of mass is below the bar.

Q3. If a hammer is thrown in the air…

Answer: All of the above

It will rotate around its center of mass.

The center of mass will follow a parabolic trajectory.

The center of mass will change through the flight.

Exp: there are three sort of natural axes you could pick for a hammer: the long axis through the hammer, one in line with the hammer head (head through claw) that runs through the center of mass, and one that's in line with the narrow width of the head. all of these have moments of inertia associated with them that are different.   

Q4. The center of mass must be located at a physical point on the object.

Answer: False

Exp: sometimes the center of mass doesn't fall anywhere on the object. the center of mass of a ring for example is located at its center, where there isn't any material.

Q5. Where is the center of mass on a hula-hoop?

Answer: In the center of the hula-hoop, where there is no mass

Exp: The center of mass is at the center (from symmetry considerations), yet there is clearly no mass at the center of the hoop