Question

what is the force which pulls the pen down​

Answer 1

Answer:

Objects or things fall towards the earth because it pulls them. This force is called the force of gravity, or just gravity. This is an attractive force. The force of gravity acts on all objects. The force of gravity acts on all of us all the time without our being aware of it.

Answer 2

Explanation:

friction force

So kinetic friction acts both on the pen and the notebook in opposite directions. The pen exerts friction force in the direction of it's motion on the notebook and the notebook exerts a friction force on the pen in the opposite direction of the pen's motion.