The water level in a tank is 20 m above the ground. a hose is connected to the bottom of the tank, and the nozzle at the end of the hose is pointed straight up. the tank is at sea level, and the water surface is open to the atmosphere. in the line leading from the tank to the nozzle is a pump, which increases the pressure of water. if the water jet rises to a height of 30 m from the ground, determine the minimum pressure rise supplied by the pump to the water line. take the density of water to be ρ = 1000 kg/m3.

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

The focal length of a relaxed human eye is approximately 1.7 cm. when we focus our eyes on a close up object, we can change the refractive power of the eye by about 16 diopters. (a) does the refractive power of our eyes increase or decrease by 16 diopters when we focus closely? explain. (b) calculate the focal length of the eye when we focus closely.

Carbon 14 is a naturally occurring stable