Hand written formula on 5\"x3\" card allowed. Both sides OK. You may use own cal
ID: 1411336 • Letter: H
Question
Hand written formula on 5"x3" card allowed. Both sides OK. You may use own calculator. C ell phones in power off mode, li.se extra sheets,f needed Q. A stone is thrown at a speed of 35.0 m/s at an of 20degree above horizontal from the cliff of a tower of height 120.0 m. (i) (low much lime does i, take t, ir stone to reach the ground? (,i) How far is i. from The foot of the rower when,t reaches the ground (...) What are the magnitude and the direction of the value of the stone when,this the ground? (iv) Mow high does this .stone go above point of throw?Explanation / Answer
i) to reach the ground, stone have to travel 120 m in vertical downward
direction.
initial vertical velocity, uy = 35sin20 = 11.97 m/s
y = - 120 m
a = -9.8 m/s^2
applying y = uy*t + a*t^2/2
-120 = 11.97t - 4.9t^2
t = 6.32 sec
ii) d = vx * t = (35 cos20)(6.32) = 207.86 m
iii) vx = 35cos20 =32.9
vy = 11.97 - (9.8 * 6.32) =50 m/s
magnitude = sqrt(vx^2 + vy^2) = 60 m/s
direction = tan^-1(vy/vx) = 56.7 deg below horizontal.
iv) maximum height will be when vertical velocity is zero.
vy^2 - uy^2 = 2aH
0^2 - 11.97^2 = 2(-9.8)(H)
H = 7.31 m
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