Unit - 2.2 Speed And Velocity — PHYSICS STD 7 — Question

Given below statement is incorrect. Write the correct statement :
On heating, the bimetallic strip (brass and iron) bends in such a way that the brass is on the inner side while iron is on outer side of the bend.

A piece of paper appears black in sunlight. What will be it£ colour when seen in red light ?

Why are musical instruments provided with more than one string ?

Given below statement is incorrect. Write the correct statement :
A teacher taking a class while standing, does work.

Explain the following :Why do the birds puff up their feathers on a cold day?

State the factors on which the pitch of a sound depends.

The outer case of the bell in a temple is made big. Give a reason.

How does the density of water changes when it is heated from 4°C to 10°C ?

Name the type of energy (kinetic or potential) possessed by the following:
A bullet fired from a gun.

Given below statement is incorrect. Write the correct statement :
When the sound travels in air, the particles of air vibrate differently compared to the vibrations of the vibrating body.