Question

Science I Pg no 29 Q 5

Answer 1

Question 1:

(a) What remains constant in uniform circular motion ?

(b) What changes continuously in uniform circular motion ? ‘

Solution :

(a)Speed

(b)Direction of motion

Question 2:

State whether the following statement is true or false :

Earth moves round the sun with uniform velocity.

Solution :

No, earth moves round the sun with uniform speed, but its velocity changes continuously.

Question 3:

A body goes round the sun with constant speed in a circular orbit. Is the motion uniform or accelerated ?

Solution :

The motion is accelerated.

Question 4:

What conclusion can you draw about the velocity of a body from the displacement-time graph shown below :

lakhmir-singh-physics-class-9-solutions-motion-2

Solution :

It represents uniform velocity.

Question 5:

Name the quantity which is measured by the area occupied under the velocity-time graph.

Solution :

Distance travelled by the moving body .

Question 6:

What does the slope of a speed-time graph indicate ?

Solution :

The slope of a speed-time graph indicates acceleration.

Question 7:

What does the slope of a distance-time graph indicate ?

Solution :

The slope of a distance-time graph indicates speed.

Question 8:

Give one example of a motion where an object does not change its speed but its direction of motion changes continuously.

Solution :

Motion of moon around the earth.

Question 9:

Name the type of motion in which a body has a constant speed but not constant velocity.

Solution :

Uniform circular motion.

Question 10:

What can you say about the motion of a body if its speed-time graph is a straight line parallel to the time axis ?

Solution :

The Speed of the body is constant or uniform.

Answer 2

The answer is:

Hydrogen,Hydrogen,

Chlorine,Helium,Florine