Mechanical Engineering Answers

A piston cylinder device contains 0.2 kg of water initially at 800 kPa and 0.06 m3. Now 200 kJ of heat is transferred to the water while its pressure is held constant. Determine the final temperature of the water. Also, show the process on a T-V diagram with respect to saturation lines.
[ 721.1oC]

Two systems have the following equations of state, where R is the gas constant per mole. The mole numbers are N1 = 3 and N2 = 5. The initial temperatures are T1 = 175 K and T2 = 400 K. What is the temperature once equilibrium is reached (in Kelvin)?

A wagon of mass 50 tones, starts from rest and travels 30 meters down a 2% grade and strikes a post with bumper spring as shown in Figure below. If the rolling resistance of the track is 60 N/t, find the velocity with which the wagon strikes the post. Also find the amount by which the spring will be compressed, if the bumper spring compresses 2 mm per 30 kN force.

Air at 6.9 bars 260oC is throttled to 5.5bars before expanding through a nozzle to a pressure of 1.1 bars. Assuming that the air flows reversibly in steady flow through the nozzle, and that no heat is rejected. Calculate the velocity of the air at exit from the nozzle when the inlet velocity is 100 m/s.

Assume for perfect gas h = cpT and for throttling process T1 = T2

Calculate the internal energy and enthalpy of 1kg air occupying 0.05m3 volume at 20 bars. If the internal energy is increased by 120 kJ as the air is compressed to 50 bars, calculate the new volume occupied by 1 kg of air.

An object starts from rest with an acceleration of 5m/s2 along a straight line. Find the speed and distance travelled after 6 seconds what use the average speed during those
6 seconds?

An automobile moving at a constant velocity of 50 ft/s passes a gasoline station. Two
seconds later, another automobile leaves the gasoline station and accelerates at the
constant rate of 6 ft/s2. How soon will the second automobile overtake the first?

A pickup truck moving at 34 m/sec must come to a stop in a distance of 196 meters to
avoid hitting a boulder that has fallen onto the road. How much time does the driver
have to avoid an accident?

A car travels a distance of 350 miles in 5.0 hours. Find its average speed.