Lucas has been challenged to increase the efficiency of a device he is redesigning. his goal is 90 percent efficiency. the work input of the device is fixed at 10 j, so lucas is trying to improve work output. how many joules of work output should lucas aim for to attain his goal of 90% efficiency?

Astone is dropped from the upper observation deck of a tower, 250 m above the ground. (assume g = 9.8 m/s2.) (a) find the distance (in meters) of the stone above ground level at time t. h(t) = (b) how long does it take the stone to reach the ground? (round your answer to two decimal places.) s (c) with what velocity does it strike the ground? (round your answer to one decimal place.) m/s (d) if the stone is thrown downward with a speed of 2 m/s, how long does it take to reach the ground? (round your answer to two decimal places.) s