Rawly has a mass of 79.0 kg, and he is sledding down a hill that is 29.5 m tall. As he goes down the hill, his gravitational potential energy is converted into kinetic energy. When he has descended 21.0 m down the hill, how much kinetic energy and gravitational potential energy does he have? A. GPE=16,300 J; KE=6590 J. B. GPE=6590 J; KE=16300 J. C. GPE=22900 J; KE=6590 J. D. GPE=0 J; KE= 22900 J

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 sun generates both mechanical and electromagnetic waves. which statement about those wave is true?

Which situation will have the highest resistance? a.long wire and high temperatureb.short wire and high temperaturec.long wire and cold temperaturedshort wire and low temperature