Question

(a) One end of a steel girder in a bridge is not fixed, but is kept on rollers. Give the reason.

(b) Describe an experiment to show that air expands on heating.

Answer 1

(a) One end of a steel girder in a bridge is not fixed, but is kept on rollers because if there is any rise in temperature of atmosphere, the grinder can freely expand without affecting the pillars.

(b) Take an empty bottle, attach a rubber balloon to its neck. Initially, the balloon is deflated. Place the bottle in a container filled with boiling water. After some time you will notice that the balloon gets inflated.this happens because of the air inside the bottle expands on heating and it fills the balloon. Take out the bottle out of the container and allow it to cool itself. We will notice that the balloon gets deflated and it collapses.