Answer: A piston-filling fountain pen has a piston — just like in a car — inside the barrel. This piston goes down to expel air or ink and then back up, pulling ink into the barrel. The typical process is very simple, assuming the pen is clean and dry: Push the piston down, expelling any air in the barrel
Answer: Yes.
Explanation:
Assuming Earth and Moon are isolated is space, it is possible to have a point where Earth and Moon will pull at an object with equal force.
That point will be closer to the Moon than the Earth because Moon's gravitational field strength is weaker than Earth's gravitational field strength.
Answer:

Explanation:
As we know that system of two boxes are moving on frictionless surface
So here if two boxes are considered as a system
then we have






Now since we know that both the boxes are moving together so force applied by first box on other box is given as


