Question

A stationary object at $ 4{}^\circ C $ and weighing 3.5 kg falls from a height 2000 m on a snow mountain at $ 0{}^\circ C $ . If the temperature of the object just before hitting the snow is $ 0{}^\circ C $ and the object before comes to rest immediately $ (g=10\text{ }m/{{s}^{2}}) $ and latent heat of ice $ =3.5\times {{10}^{5}} $ J/s), then the object

• A. 2kg of ice
• B. 200 g of ice
• C. 20g ice
• D. 2g ice

Answer 1

Answer: (B)

Law of conservation of energy is valid. Potential energy is the energy possesed by a body due. to its weight. It is given by
$ PE=mgh $ where, m is mass, g acceleration due to gravity and h is height This potential energy is utilized in giving latent heat to ice
$ mL=mgh $
Given $ ~m=3.5kg,\text{ }g=10m/{{s}^{2}},\text{ }h=2000m $
$ L=3.5\times {{10}^{5}}J/s $
$ m=\frac{mgh}{L} $
$ m=\frac{3.5\times 10\times 200}{3.5\times {{10}^{5}}} $
$ m=02 $ kg of ice
Also, $ 1\,kg={{10}^{3}}g $ $ m=200\text{ }g $ of ice