Tissues — Science STD 9 — Question

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.

Explain the significance of the symbol H.

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.

How are high yielding breeds of poultry advantageous over indigenous breeds?

A man throws a ball weighing 500g vertically upwards with a speed of 10m/s.

1. What will be its initial momentum?
2. What would be its momentum at the highest point of its flight?

A boy throws a rubber ball vertically upwards. What type of work, positive or negative, is done:

1. By the force applied by the boy?
2. By the gravitational force of earth?

When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?

What are ultrasonic waves? Name two animals which produce ultrasonic waves.