A water-skier with a mass of 68 kg is pulled with a constant force of 870 N by a speedboat. A wave launches him in such a way that he is temporarily airborne while still being pulled by the boat, as shown in the image below. Assuming that air resistance can be ignored, what is the vertical acceleration that the water-skier experiences on his return to the water surface? (Recall that g = 9.8 m/s2) A. -13.6 m/s2
B. -17.1 m/s2
c. -22.5 m/s2
D. -9.8 m/s2

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.

Will a heavier bowling ball hit pins better than a lighter bsll

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?