Sound — Science STD 9 — Question

What are the quantities on which the amount on which the amount of work done depends? How are they related to work?

Why does a sharp knife cut objects more effectively than a blunt knife?

On what factors does the gravitational potential energy of a body depend?

If two equal weights of unequal volumes are balanced in air, what will happen when they are completely dipped in water? Why?

State whether the following objects possess kinetic energy, potential energy, or both:

1. A man climbing a hill.
2. A flying aeroplane.
3. A bird running on the ground.
4. A ceiling fan in the off position.
5. A stretched spring lying on the ground.

How many moles are there in 34.5g of sodium?
(Atomic mass of Na = 23u)

To take the boat away from the bank of a river, the boatman pushes the bank with an oar. Why?

Why is a liquid (the hydraulic fluid) used to operate the brakes in a car?

Separate the following into physical and chemical changes:
Sublimation of a solid, Decomposition of water into hydrogen and oxygen by passing electric current, Formation of clouds, Making a fruit salad from raw fruits, Dissolving carbon dioxide in water.