MNE 220 Spring 2026
HW#1
Due on Tuesday, Feb 3, in class
Guidelines: On the working sheets, you should (i) write the equations first before plugging in the
numbers, and (ii) include the unit for all physical values. You will loss point if you don’t follow
this guideline, even though you have a correct final answer.
1. The Phoenix with a mass of 380 kg was a spacecraft used for exploration of Mars. Determine
the weight of the Phoenix on Mars. The acceleration of gravity is 3.73 m/s2 on Mars. (2 points)
2. The specific volume of 5 kg of water vapor at 8.5 MPa, 440°C is 0.03498 m3/kg. Determine
(a) the volume occupied by the water vapor; (2 points)
(b) the amount of water vapor present, in gram moles. (2 points)
3. A vertical piston–cylinder assembly containing a
gas
is
placed
on
a
hot
plate,
2
where A=0.015 m , m=20 kg, and patm=1 bar. The
piston initially rests on the stops. With the onset of
heating, the gas pressure increases. The piston
moves smoothly in the cylinder. Let g=9.81 m/s2.
At what gas pressure does the piston start rising?
(Hint: plotting all forces applied on the piston;
piston starts rising when the upward forces are
larger than the downward forces) (3 points).
4. The tank, shown in the figure, contains a gas at a pressure
of 1.7 bar. The local atmospheric pressure is patm=1 bar.
The manometer liquid is mercury, which has a density of
13.59 g/cm3. Let g=9.81 m/s2. Determine L. (2 points).
5. Water in a swimming pool has a temperature of 27°C.
Express this temperature in K, °F, and °R. (3 points).