What speed should a spaceship of mass 5.21 x 107kg moving around a planet only by the gravitational force be, if the distance between them is 6.27 x 108 m
and the mass of the planet is 4.76 x 1026 kg? Estimate G as 6.67 * 10-11 N (m/kg)

A. 7.12 x 103 m/s
B. 6.23 x 103 m/s
С. 4.25 x 103 m/s
D. 7.43 105 m/s
E. 7.25 x 103 m/s

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