Afarmer is to pump water at 70°f from a river to a water storage tank nearby using a 125-ft-long, 5-in-diameter plasticpipe with three ﬂanged 90° smooth bends. the water velocity near the river surface is 6 ft/s, and the pipe inlet is placed inthe river normal to the flow direction of water to take advantage of the dynamic pressure. the elevation differencebetween the river and the free surface of the tank is 12 ft for a ﬂow rate of 1.5 ft3/s and an overall pump efficiency of 70percent, determine the required electric power input to the pump.
heat transfer through conduction is a slow process and both conduction and convection require material medium
explanation & answer:
assuming a smooth transition so that there is no abrupt change in slopes to avoid frictional loss nor toppling, we can use energy considerations.
initially, the cube has a kinetic energy of
ke = mv^2/2 = 10 lbm * 20^2 ft^2/s^2 / 2 = 2000 lbm-ft^2 / s^2
at the highest point when the block stops, the gain in potential energy is
pe = mgh = 10 lbm * 32.2 ft/s^2 * h ft = 322 lbm ft^2/s^2
by assumption, there was no loss in energies, we equate pe = ke
322h lbm ft^2/s^2 = 2000 lbm ft^2/s^2
h = 2000 /322 = 6.211 (ft)
distance up incline = h / sin(30) = 12.4 ft
a light emitting diode (led) is one of the latest inventions and is extensively used these days. from your cell phone to the large advertising display boards, the wide range of applications of these magical light bulbs can be witnessed almost everywhere. today their popularity and applications are increasing rapidly due to some remarkable properties they have. specifically, leds are very small in size and consume very little power.
the answer would be a