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ENG. Solutions

Replace this loading by an equivalent resultant force and specify its location, measured from point O.

Mechanical Engineering Solutions

Replace the distributed loading by an equivalent resultant force, and specify its location on the beam, measured from the pin at A.

Mechanical Engineering Solutions

Currently eighty-five percent of all neck injuries are caused by rear-end car collisions. To alleviate this problem, an automobile seat restraint has been developed that provides additional pressure contact with the cranium. During dynamic tests the distribution of load on the cranium has been plotted and shown to be parabolic. Determine the equivalent resultant force and its location, measured from point A.

Solutions

Air with a speed of { V }_{ o } flows over a long bar that has a 15◦ wedge-shaped cross-section. The pressure variation, as represented using the coefficient of pressure, is shown in the following sketch. On the west face of the bar, the coefficient of pressure is everywhere equal to +1. On the northeast face, the coefficient of pressure varies linearly from -2 to 0, and on the south face the variation is linear from +1 to 0. Determine the coefficient of drag and the coefficient of lift.

Civil & Environmental Engineering Solutions

Air with a speed of 30 m/s and a density of { 1.25 kg/m }^{ 3 } flows normal to a rectangular sign of dimension 5.5 m by 7.5 m. Find the force of the air on the sign.

Civil & Environmental Engineering Solutions

A student is modeling the drag force on the fins of a model rocket. The rocket has three fins, each fabricated from 1/16 in.-thick balsa-wood to a dimension of 2.5 × 1 in. The coefficient of drag for each fin is 1.4, and the fin is subjected to air with a speed of 100 mph and a density of 0.00237 { slug/ft }^{ 3 } . Determine the total drag force on the fins. Since the fins are not streamlined, assume that drag on a given fin is based on the projected area (not the planform area).

Civil & Environmental Engineering Solutions

For a bicycle racer who races on the road, a typical speed is 40 kph, the coefficient of drag is about 0.88, and the frontal area is about { 0.36 m }^{ 2 } . Determine the power required to overcome wind drag when there is (a) no headwind and (b) a headwind of 15 kph.

Civil & Environmental Engineering Solutions

During the preliminary design of a submarine, a designer assumes that the drag force will be equal to the drag on a streamlined body that has a diameter of 1.5 m and a length of 8 m. The design speed is 10 m/s, the submarine will operate in 10 ◦C water (kinematic viscosity is ν = 1.31 × { 10 }^{ −6 } { m }^{ 2 }/s), and the sub will be powered by an electric motor with an efficiency of 90%. Determine the power that will be consumed by the motor.

Civil & Environmental Engineering Solutions

Find the terminal velocity of a 18-cm diameter, helium-filled balloon. The balloon material has a mass of 2 g, the helium in the balloon is at a pressure of 2.5 kPa, and the balloon is moving through air at 20 ◦C.

Civil & Environmental Engineering Solutions

Methane at 25◦C (R = 518 J/kg/K, k = 1.31) is flowing in a pipe at 400 m/s. Is the flow subsonic, sonic, supersonic, or hypersonic?

Civil & Environmental Engineering Solutions

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