Mech-ing

  Question: Two trains of length 200 m and 300 m are running towards each other on parallel lines at 90 km/h and 60 km/h, respectively. In what time will they be clear of each other from the moment they meet? Answer: Determine the relative velocity of the trains running towards each other. Convert the relative velocity from km/h to m/s. Determine the total distance required to travel by the train to cross each other. Calculate the time required by the trains to cross each other. Thus, the time required by the trains to cross each other is 12 seconds.

Question: A container, in the shape of a rectangle prism with dimensions  , and , is filled with an ideal gas and sealed. The average force exerted by the gas molecules on the bottom of the container is . There are moles of gas in the container and the temperature of the gas is . What is , the height of the container? Answer: Here, the volume of the gas is equal to the volume of the container. So write the equation of the volume of the gas.   ......(1) Write the equation of the area of the bottom of the container.  ......(2) The ideal gas law equation is, Here, is the pressure of the ideal gas, is the volume of the ideal gas, is the number of the moles of the ideal gas, is the universal gas constant and is the temperature of the ideal gas. According to definition of the pressure, write the equation of the pressure in terms of and .  ......(3) From the above equation (1), (2), (3) and the ideal gas law equation.