Solution to Activity 9.6 of NCERT Class 9 Science Chapter 9 Gravitation

6. Complete Activity 9.6 (Page 109).

• Take a beaker filled with water.

• Take a piece of cork and an iron nail of equal mass.

• Place them on the surface of water.

• Observe what happens.

Answer:

Aim: To place the piece of cork and an iron nail of equal mass on the surface of water, observe what happens and conclude based on that.

Materials Required: Beaker, water, piece of cork, iron nail of equal mass.

Procedure:

(i) The beaker is filled with water.

(ii) Place the piece of cork and the iron nail on the surface of the water and observe what happens

Observations:

You will observe that the piece of cork floats while the iron nail of equal mass sinks.

Cork floats on water while the nail sinks. — **Cork and Nail:** The cork floats on water while the nail of equal mass sinks. Let us find out why.

Conclusions:

The density of cork is less than the density of water. This means that the upthrust of water acting upwards on the cork is greater than the weight of the cork acting downwards. So it floats.
The density of an iron nail is more than the density of water. This means that the upthrust of water acting upwards on the iron nail is less than the weight of the nail acting downwards. So it sinks.
Objects of density less than that of a liquid float on the liquid. The objects of density greater than that of a liquid sink in the liquid.

“• Take a beaker filled with water.

• Take a piece of cork and an iron nail of equal mass.

• Place them on the surface of water.

• Observe what happens.” – Solved.