Answer:

Explanation:
As per mechanical energy conservation we can say that here since friction is present in the barrel so we will have
Work done by friction force = Loss in mechanical energy
so we will have

here we know that



Initial compression in the spring is given as



now from above equation




Answer:
Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces. Archimedes' principle is a law of physics fundamental to fluid mechanics. It was formulated by Archimedes of Syracuse.
Answer:
15 N
Explanation:
According to Newton's third law of motion, to every action, there is an equal and opposite reaction. This reaction is equal in magnitude to the force acting but in an opposite direction.
Now, if the book weighs 15 N, an opposite equal force will be: N = -15 N
But the magnitude of this will be the absolute value which is 15N.