Answer:
The mass of the cargo is 
Explanation:
From the question we are told that
The radius of the spherical balloon is 
The mass of the balloon is 
The volume of the spherical balloon is mathematically represented as
substituting values
The total mass the balloon can lift is mathematically represented as
where 
is the density of helium with a value of
and 
is the density of air with a value of
substituting values
Now the mass of the cargo is mathematically evaluated as
Answer:
An apple hanging at a branch has potential energy due its position. It can be written as PE= mgh where m is the mass of the apple h is the distance between the apple and the ground and g is the acceleration due to gravity.
as the apple falls from the tree it loses its potential energy and gains kinetic energy due to the movement of the apple. Its kinetic energy will be given by KE= 1/2mv² where m is the mass of the apple and v is the speed with which the apple falls.
As the apple falls the height or the distance reduces and PE becomes reduces. But it gains Kinetic energy due to its speed.
But when the apple falls to the ground and comes to rest its kinetic energy is converted to potential energy.
thus the total energy remains the same. it changes from one form to the other but remains unaltered.
The answer is b
300,000 km
