I need #4 and if you can do number(#2) I am grateful. I don\'t need number 3 2)

Question

I need #4
and if you can do number(#2) I am grateful.
I don't need number 3

2) 25 pts.A person drops a stone into a well shaft. Three seconds after the person drops the stone, he hears the sound of the stone hitting the bottom of the well shaft. Find the depth, in feet, of the well shaft. Assume the sound wave travels with a constant velocity of 1120 ft/sec. g 32.2 ft/sec/sec 25 pts. Water in a river flows with a component downstream (x -direction) of 6 m/s and a component across the stream (y-direction) of 4 m/s. A boat is attempting to cross the river. The velocity of the boat relative to the water is 20 m/s at an angle of 70 degrees with respect to the x-axis. Determine the velocity of the boat relative to the shore. 3) 4) 25 pts. The following figure shows a gun emplacement and a stationary tank. The shellis fired from the gun and hits the tank. a) How long is the shell in flight? b) What is the value of the distance "x"

Explanation / Answer

2) LET DEPTH OF THE well be d

then time taken for the coin to reach the bottom = t1

time taken by sound to come back = t2

d = 0.5gt1^2

t1 = sqrot(2d/g)

and t2 = d/v

where v is speed of sound in air, v = 1120 ft/s

hence t1 + t2 = 3 = sqroot(2d/32.2) + d/1120

3360 - d = 279.129*sqroot(d)

11289600 + d^2 - 6720d = 77912.998641*d

d^2 - 84632.998641d + 11289600 = 0

solving for d

d = 133.60 ft

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