Answer: The given statement is false.
Explanation:
According to Newton's third law of motion, every action has an equal and opposite reaction. So, when we apply force in one direction on an object then the object also applies a force in the opposite direction.
Hence, it is true that two forces in each pair of forces act in opposite directions.
For example, when we push a wooden box of 20 kg in the forward direction then the box will also apply a force in the opposite direction.
But the statement two forces in each pair can either both act on the same body or they can act on different bodies is false.
Density is given as

now we have to convert this density into 
now we have





Answer:
The energy stored is: 62.5 Joules
Explanation:
Given
--- spring constant
--- stretch
Required
The amount of energy
This is calculated as:




Yes all those are correct, but I don't know what the question was
The shape of which the pebble sized particles that makes up the rock is more of a rounded shape as they are bits and in circular formation, depicting it to be more rounder in which are particles that is made up in a rock. They can be in pebble sized or much more smaller than that when in bits.