A stone is dropped from the upper observation deck of a tower, 250 m above the g

Question

A stone 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) = 2504.9t2 Correct: Your answer is correct. (b) How long does it take the stone to reach the ground? (Round your answer to two decimal places.) 7.14 Correct: Your answer is correct. s (c) With what velocity does it strike the ground? (Round your answer to one decimal place.) -70 Correct: Your answer is correct. m/s (d) If the stone is thrown downward with a speed of 3 m/s, how long does it take to reach the ground? (Round your answer to two decimal places.)

Explanation / Answer

From the given question,

height of the tower(h)=250 m

acceleration due to gravity(g)=9.8 m/s2

a)distance travelled by stone in time t =0(t)+(1/2)gt2

=(1/2)(9.8)t2

=4.9t2

Distance of the stone above ground level(x)= 250-4.9t2

b)To reach ground, 250-4.9t2=0

t=7.14 s

c) let the stone strikes with velocity v

v=u+gt

=0+(9.8)(7.14)

=69.97 m/s

d)Initial speed=3 m/s

s=ut+(1/2)gt2

250=3t+(1/2)(9.8)t2

solving we get

t=6.84 s

The stone will the 6.84 seconds to reach ground.

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