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A stone has a mass of 5kg. If it takes the stone 4 sec to fall freely to the ground, calculate it's initial height above the ground, and the force with which the stone hit the ground.
The linear density of a thin rod is given by p =cx, where c is a constant and x is the distance
measured from one end. If the rod is of length b, find the center of mass.
A uniform solid ball has a few turns of light string wound around it. If the end of the string
is held steady and the ball is allowed to fall under gravity,what is the acceleration of the
center of the ball? (Assume the string remains vertical.)
A 1305 kg test car travels around a flat circular track that is 2.15 km long (circumference). If the coefficient of friction between the car’s tires and the track is 1.20 will the car be able to drive a speed of 55.7 m/s and stay on the track?
The emf induced in the armature of a shunt generator is 596 V. The armature
resistance is 0.1Ω
(a) Compute the terminal voltage when the armature current is 460A.
(b) The field resistance is 110Ω. Determine the field current, and the current and power delivered to the external circuit
A shunt motor armature resistance 0.08Ω is connected to 120V mains. With 50A in the armature, what are the back emf and the mechanical power developed within the armature?
1. Determine the discharge over an uncontracted horizontal weir that is 1.5 m high and 4.5 m long. The upstream depth is 2.2 m. Determine the Ink height if the same discharge was desired without exceeding an upstream depth of 1.8 m?
2. Determine the discharge over a standard contracted weir when the upstream water depth is 2.1 m. The weir (one end contraction) is 1.8 m high and has a 1.8 m overflow length. Also determine the approach velocity head in the 4-m-wide channel. Is it significant?
1. A 10-cm ASME flow nozzle is installed in a 20-cm (horizontal) waterline. The attached manometer contains mercury (SG = 13.6) and water and registers a pressure difference of 42-cm. Calculate the discharge in the pipe.
2. Determine the discharge over an uncontracted horizontal weir when the upstream water depth is 7.0 ft. The sharp-crested weir is 9.0 ft long and 6.0 ft high.
1. The maximum flow rate in an 8-in. diameter (horizontal) waterline is 4.3 cfs. If a 4-in. Venturi meter is installed in the pipe to measure flow, estimate the necessary length of a vertical U-tube scale for the differential water-mercury (SG = 13.6) manometer.
2. A 50-cm diameter (horizontal) pipe contains a 20-cm Venturi meter. Determine the flow rate if the pressure difference reading between the throat and entry section in a water-mercury (SG = 13.6) manometer is 1.46 m.
6-36. Reconsider the helicopter in Prob. 6-35, except that it is hovering on top of a 2200-m-high mountain where the air density is 0.987 kg/m3. Noting that the unloaded helicopter blades must rotate at 550 rpm to hover at sea level, determine the blade rotational velocity to hover at the higher altitude. Also determine the percent increase in the required power input to hover at 2200 m altitude relative to that at sea level. Answers. 601 rpm, 9.3 percent
6-38 Water flowing in a horizontal 25-cm-diameter pipe at 8 m/s and 300 kPa gage enters a 90° bend reducing section, which connects to a 15-cm-diameter vertical pipe. The inlet of the bend is 50 cm above the exit. Neglecting any frictional and gravitational effects, determine the net resultant force exerted on the reducer by the water. Take the momentum-flux correction factor to be 1.04.
