Question

1A)For a certain transverse wave, the distance between two successive troughs is 1 m, and four crests pass a given point along the direction of travel every 5 s. What is the wave speed?

1B) Calculate the amount of energy required to convert 2 kg of ice at 0oC to water at 80oC. (Note: cwater = 4186 J/kgoC and Lf,water = 3.4x105 J/kg).

1C) A thermodynamic system undergoes a process where its internal energy increases by 200 J. During this time interval, 75J of heat is transferred from the system. How much energy in the form of work is transferred? 1D) Calculate the approximate total translational kinetic energy of 1.5-mol of an ideal gas at a temperature of 75C.

Answer 1

A)

distance between two successive crests of a wave is wavelength

so,

wavelength = 1 meter

frequency = 4/5 = 0.8 Hz

so,

speed = wavelength * frequency

speed = 0.8 m/s

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B)

heat required to turn ice to water = 3.4e5 * 2 = 6.8e5 J

heat required to bring the temperature of water from 0 to 80 = 2 * 4186 * ( 80 - 0) = 669760 J

total heat required = 1.35e6 J

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C)

U = Q - W

as internal energy increases, it is positive, as heat is transferred from the system , it is negative

200 = - 75 - W

so,

W = -275 J