Tissues — Science STD 9 — Question

What is sonar? Explain its use.

State two characteristics of matter demonstrated by:
Brownian motion.

Give reason for the following observation:
The smell of hot sizzling food reaches us even from a considerable distance but to get the smell form cold food, we have to go close to it.

Why is sodium a metal whereas carbon non-metal?

Give one example of an Indian and foreign poultry breed which when crossed produce an improved variety. List any one desirable trait expected from such cross breeding.

Calculate the change in momentum of a body weighing 5kg when its velocity decreases from 20m/s to 0.20m/s.

A car is moving with velocity 108km/h. If driver of the car want to change its velocity from 108km/h to 90km/h in two minute Mass of the car is 300kg. What force applied by the brakes on the tyres?