Assuming the ball\'s initial velocity was 51° above the horizontal and ignoring

Question

Assuming the ball's initial velocity was 51° above the horizontal and ignoring air resistance, what did the initial speed of the ball need to be to produce such a home run if the ball was hit at a point 0.9 m (3.0 ft) above ground level? Assume that the ground was perfectly flat. Problem 3.53 According to the Guinness Book of World Records, the longest home run ever measured was hit by Roy "Dizzy" Carlyle in a minor league game. The ball traveled 188 Im (618 ft) before landing on the ground outside the ballpark. Express your answer using two significant figures 47.37 m/s Submit My Answers Give Up Incorrect; Try Again; 5 attempts remaining Part B How far would the ball be above a fence 3.0 m (10 ft) high if the fence was 116 m (380 ft) from home plate? Express your answer using two significant figures In Submit My Answers Give Up

Explanation / Answer

A)

Let V be the initial speed of the ball. Because the ball was hit angle an angle, there are two speed components: one is in x-direction, and the other one is in the y-inderect. The ball travels at a constant speed horizonally but accelerates vertically.

Break down the intial speed

Vx = Vcos45

Vy = Vsin45

find the time it takes the ball to hit the ground 188m away horizonally

x = vt

188 = Vcos51 * t

t = 188 / Vcos51

Xf = .5at^2 + Vt + Xi

Xf = final position (0m)

Xi = initial position (.9m)

a = acceleration

t = time

V = speed in y-derection

we just found the time, which is 188 / Vcos51, plug it in

0 = .5(-9.8)(188 / Vcos51)^2 + Vsin15 * (188 / Vcos51) + .9

-.9 = -4.9(188 / Vcos51)^2 + 232.16

-233.06 = -4.9(188 / Vcos51)^2

47.56 = (188 / Vcos51)^2

6.897 = 188 / Vcos51

6.897 * Vcos51 = 188

V = 188 / (6.897cos51)

V = 43 m/s

The ball was hit with the speed of 43m/s

B)

Find the it takes the ball to travel 116m

x = vt

116 = 43cos51 * t

t = 4.287s

Xf = .5at^2 + Vt + Xi

Xf = .5(-9.8)(4.287)^2 + 43sin51 (4.287) + .9

Xf = 54m

the ball was 54.1 - 3 = 51m above the fence

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