Some curious students hold a rolling race by rolling four items down a steep hill. The four items are a solid homogeneous sphere
, a thin spherical shell, a solid homogeneous cylinder and a hoop with all its mass concentrated on the hoop's perimeter. All of the objects have the same mass and start from rest. Assume that the objects roll without slipping and that air resistance and rolling resistance are negligible. For each statement below, select True or False.
a) Upon reaching the bottom of the hill, the hoop will have a larger rotational kinetic energy than any of the other objects will when they reach the bottom of the hill.
A: True B: False
b) The hoop reaches the bottom of the hill before the homogeneous cylinder.
A: True B: False
a) Upon reaching the bottom of the hill, the hoop will have a larger rotational kinetic energy than any of the other objects will when they reach the bottom of the hill.
A: True B: False
b) The hoop reaches the bottom of the hill before the homogeneous cylinder.
A: True B: False
1 answer:
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If the distance between two charges is halved, the electrical force between them increases by a factor 4.
In fact, the magnitude of the electric force between two charges is given by:
where
k is the Coulomb's constant
q1 and q2 are the two charges
r is the separation between the two charges
We see that the magnitude of the force F is inversely proportional to the square of the distance r. Therefore, if the radius is halved:
the magnitude of the force changes as follows:
so, the force increases by a factor 4.
In fact, the magnitude of the electric force between two charges is given by:
where
k is the Coulomb's constant
q1 and q2 are the two charges
r is the separation between the two charges
We see that the magnitude of the force F is inversely proportional to the square of the distance r. Therefore, if the radius is halved:
the magnitude of the force changes as follows:
so, the force increases by a factor 4.