What does a pulley system need in order to reduce the force needed to lift an object?
A. exactly one pulley that has a fixed position
B. No pulley system can reduce the force needed to lift an object.
C. at least one movable pulley
D.
a load that is not too heavy

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