(a) if the masses of earth and the moon were both doubled, by how much would the radius of the moon's orbit about earth have to change if its speed did not change? (assume that rem is the mean distance between earth and the moon before changing of the mass, r′em is the mean distance between earth and the moon after changing of the ) by how much would its speed have to change if its radius did not change? justify your answer.

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