Answer A rock of mass = 4 kg is dropped from the building of height h = 25 meter

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A rock of mass = 4 kg is dropped from the building of height h = 25 meters with initial velocity pointing downward of vo = 1 m/s. HINT: Use the mechanical energy conservation law. What is the rock's kinetic energy E(kinetic)final when it hits the ground ? What will be the rock's speed v final when it hits the ground ? How much heat energy (in kcal) is needed to change the liquid water at 100 degree C into water vapor at the temperature of 175 degree C. Mass of water is 6 kg. (Hint: Note that there is a change in the phase from liquid to gaseous phase (vapor). Water boils at T = 100 degree C. First, estimate the heat needed to turn the liquid water into vapor. Then, calculate the heat energy needed to increase the temperature of it.) Specific heat capacity of ice: c(ice) = 0.5 kcal/kg degree C. Specific heat capacity of liquid water: c(liquid) = 1.0 kcal/kg degree C. Specific heat capacity of water vapor: c(vapor) = 0.5 kcal/kg degree C. The latent heat of fusion (freezing) for water: Lf = 80 kcal/kg. The latent heat of vaporization for water: Lv = 540 kcal/kg.

Explanation / Answer

from newtons law, V(final)^2 = V(initial)^2 + (2accelerationxheight) where acceleration= g vinitial= 1 hence B) vfinal= sq.root of 1 + (2g25) hence A) KE= mass x Vfinal^2 / 2

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