In some countries liquid nitrogen is used on dairy trucks instead of mechanical refrigerators. a 3 hour delivery trip requires .200 m^3 of liquid nitrogen which has a density of 808 kg/m^3, assuming it is already at its boiling temperature of -195.8c, calculate the heat transfer necessary to evaporate this amount of liquid nitrogen and raise its temperature to 4.0c (nitrogen: lv=201 kj/ kg, cgas = 1040 j/kgc

Amount of necessary heat transfer, q =  

Given:

Volume of liquid Nitrogen, V = 0.200

Density of liquid Nitrogen,  

Temperature,

Temperature Rise, T' =  

Latent heat of Vaporization,

Specific heat capacity of gas,

Solution:

Now, calculation of heat transfer required to evaporate liquid nitrogen and raise its temperature is given by:

                       (1)

Now, mass, m can be given by:

Now, from eqn (1):

q =

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

e/c, where e is its total energy