When a spinning star shrinks in radius, it speeds up. Which of the following statements explains this phenomenon?
1 answer:
Answer:
B.)Angular momentum is always conserved
Explanation:
Angular momentum is given by:
where
m is the mass of the object
v is its speed
r is the distance between the object and the centre of its circular trajectory
In absence of external torques, angular momentum is always conserved. That means that for the spinning star, if its radius r decreases (because it shrinks), in order for L (the angular momentum) to be conserved, the speed (v) must increases, therefore the spinning star speeds up.
So, the correct choice is
B.)Angular momentum is always conserved
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Answer:
- No, this doesn't mean the electric potential equals zero.
Explanation:
In electrostatics, the electric field is related to the gradient of the electric potential V with :
This means that for constant electric potential the electric field must be zero:
This is not the only case in which we would find an zero electric field, as, any scalar field with gradient zero will give an zero electric field. For example:
give an electric field of zero at point (0,0,0)