Chap 3 Begin Date: 1/25/2017 12:00:00 AM-- Due Date: 9/24/2017 11:59:00 PM End D

Question

Chap 3 Begin Date: 1/25/2017 12:00:00 AM-- Due Date: 9/24/2017 11:59:00 PM End Date: 1/3/2018 12:00:00 AM (9%) Problem 6: A football player punts the ball from the ground at a 45.0° angle above the horizontal. Without an effect frorn the wind, the ball would travel 66 m before falling back to the ground Incorrect Answer The provided answer is not correct and no specific feedback is available Please view available hints and review the relevant material Close 50% Part (a) What is the initial speed of the ball in m/s? 50% Part(b) When the ball is near its maximum height it experiences a brief gust of wind that reduces its horizontal velocity by 1.1 m/s What total distance, in meters, travels the ball horizontally before returning to the ground? Grade Summary Deductions Potential x = 76.72 4% 96% sin cotan0asin atan() acotan) s cosh() 78 9 HOME cos() asn(o) tan() | | acos) sinh Submissions Attempts remaining: 2 (4% per attempt) detailed view tanh) cotanh END

Explanation / Answer

(a) let t= time tkento reach the highest point

Viy= Visin45

Vfy=0

vfy= viy+gt

0=Vi sin 45 +(-9.8) t

t=( Vi sin45)/9.8

total time in air=2t= (2 Vi sin45)/9.8

now horizontal range= Vix T

66= Vi cos 45 [( 2Vi sin45)/9.8]

66= (2 Vi2 sin45 cos45 )/9.8

Vi= 25.4 m/s

(b)time taken to reach top=( Vi sin45)/9.8= (25.4 sin45)/9.8=1.83 seconds

horizontal velocity until ball reaches highest point= Vi cos45= 25.4cos45=17.96 m/s

so horizontal distance convered while going up= X1= 17.96x1.83=32.87 m

horizontal velocity after top till the ball hits ground= 17.96-1.1=16.86m/s

horizontal distance convered while going down= X2= 16.86 x1.83=30.85 m

total horizontal distance=32.87+30.85

horizontal distance=63.7 m

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