The mass of a radioactive element at time t is given by

where

is the mass at time zero, while

is the half-life of the element.
In our problem,

, t=121.0 s and

, so we can find the initial mass

:
Answer:
Explanation:
Tension provides centripetal force in the circular motion . In circular motion work done by force = torque x angle
torque is zero as , centripetal force passes through axis of rotation that is center.
So work done by centripetal force = 0
So work done by tension on M = 0
Answer:

Explanation:
As we know that the charge per unit length of the long cylinder is given as

here we know that the electric field between two cylinders is given by

now we know that electric potential and electric field is related to each other as





Answer:
true
Explanation:
The law of conservation of charge states that whenever electrons are transferred between objects, the total charge remains the same.
Answer:
The strength of gravity decreases.
An example of that would be if you were in space; you float around because there's no gravity.