Gravitation — Science STD 9 — Question

What can you say about the motion of a body if:

1. Its displacement-time graph is a straight line?
2. Its velocity-time graph is a straight line?

Mention four advantages of fishery.

Give one example of each:

1. Asymmetry, radial symmetry and bilateral symmetry.
2. Acoelomate, pseudocoelomate and haemocoelomate.

A boy weighing 50kg climbs up a vertical height of 100m. Calculate the amount of work done by him. How much potential energy does he gain? (8 = 9.8m/s²).

A man standing 825 metres away from a cliff (steep rock) fires a gun. After how long will he hear its echo? Speed of sound in air is 33m/s.

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.