Heat — PHYSICS STD 9 — Question

Under what condition is the displacement of a body equal to the distance traveled by it?

Explain how the principle of echo is used by
The dolphin to locate small fish as its prey.

Name and state the action and reaction in the following case : A book lying on a table

Draw a neat diagram of a simple pendulum. Show on it the effective length of the pendulum and its one oscillation .

Name the factor on which the inertia of a body depends and state how does it depend on the factor stated by you .

Name two substances which expand on heating.

State the direction of incident ray which after reflection from a spherical mirror retraces its path. Give a reason to your answer.

State the purpose of ratchet in a screw gauge.

What is the cause of regular reflection?

An object covers a distance of S meters in t seconds as follows :

S (meters)	0	8	20	20	16	10	0
t (Seconds)	80	2	5	10	12	15	10

Plot a graph, taking t on X-axis and S on Y-axis. Determine the velocity of the object at time
(i) 6 s, and
(ii) 14 s.