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

Why are quilts filled with fluffy cotton?

Why is the freezing chest in a refrigerator fitted near its top?

One sunny day Aditi and her brother test two umbrellas on the terrace:

(i) one is black

(ii) other a shiny silver.

After 15 minutes, the area under the shiny silver umbrella was cooler.

Answer the following:

(i) Which umbrella absorbs more heat from sun?

(ii) Which umbrella reflected more heat radiation?

(iii) When heat reaches us from sun, it reaches in which mode?