Linear Momentum: Example Problems

Try to solve these problems before watching the solutions in the screencasts.

Example Problem 1

The aluminum elbow is bolted to a pipe, which is not shown. The bolts provide a force that anchors the elbow in place. What are the x- and y-components of this anchoring force? The diameters of the entrance and exit are D1 = 10 cm and D2 = 5 cm. The mass of the elbow is me = 2.4 kg. The mass of the water inside of it is mw = 3 kg. The volumetric flow rate of the water is Q = 15 L/s. The gage pressure of the water entering the elbow is P1 = 30 kPa. The water exits the elbow as a free jet.

Image to help visualize an example problem in the Linear Momentum Module
Example Problem 2

How much reverse thrust is developed? The diameter of the fan is 2 m. The engine is drawing in a mass flow rate of air of 500 kg/s. Air flows through the engine and is deflected at an angle of 60 degrees from the horizontal. The velocity exiting through the thrust reversers (V2) is 3 times the magnitude of the velocity entering the engine (V1).

Image to help understand an example problem in the Linear Momentum module