Answer:
a. 8p
Explanation:
We are given that
Radius of hollow sphere , R1=R
Density of hollow sphere=
After compress
Radius of hollow sphere, R2=R/2
We have to find density of the compressed sphere.
We know that


Therefore,
Volume of sphere=
Using the formula



Hence, the density of the compressed sphere=
Option a is correct.
Correct Answers is A.
The machines gives us some mechanical advantage. This means the mechanical average makes the work output greater than the work input
Simple most example is a lever. The force applied is smaller and the output work is larger as compared to input.
Option B cannot be true, as there must be a force to get some work done.
Option C and D are inverse of what a machine is designed for. A small force can be exerted through a large distance to have a large force exerted through a small distance. Common Example of this principle is a screw opener.
For heating Solid, Liquid, Gas and for cooling the opposite Gas, Liquid, Solid