What causes fire when flint stones are rubbed together? Explain.

Rakesh and Rajesh live in Rajasthan. They have never visited a hill station and never walked on snow. On a school trip to Srinagar, their teacher told them that it has already snowed in Srinagar and the whole city will be covered with snow by the time they reach there. Both Rajesh and Rakesh were excited about this. As the team reached the hotel in Srinagar on Monday morning, the teachers gave the students some free time. Rakesh and Rajesh looked outside from the hotel window and saw that the road was covered by a thin layer of Snow. They went outside and tried walking on the road but were unable to do so. They were perplexed and disappointed because they slipped and fell on the snow repeatedly. They came back inside the hotel and their teacher told them that they were unable to walk on the road because there was no friction. She asked them to read more about friction in chapter $12$of their science textbook.

How does friction make it difficult to walk on a road covered with snow?

The terms that you came across in the chapter (Friction) are hidden in the alphabet grid given below. Try to find out all of these terms by going up, down, or even diagonally forward as well as backward.

Follow the clues and solve the terms you have learned.
Across :

1. The friction acting when one body rolls over the surface of another body $(7, 8)$.
4. The frictional force exerted by fluids $(5, 8)$.
6. The overlapping or fitting together of tiny hills and grooves in the form of irregularities on two surfaces in contact.

Down:

2. A bearing that permits rolling between moving and fixed parts by means of small metal balls confined between outer and inner rings, which reduces friction $(4,7)$.
3. Substances that reduce friction.
5. The friction acting when one body slides over the surface of another body $(7,8)$ .
7. The force required to overcome friction at the instant an object starts moving from rest $(6,8)$ .