HW5 (Unit 3) Begin Date:9/7/2017 8:00:00 PMDue Date: 9/19/2017 5:00:00 PM End Da
ID: 1656049 • Letter: H
Question
HW5 (Unit 3) Begin Date:9/7/2017 8:00:00 PMDue Date: 9/19/2017 5:00:00 PM End Date: 9/19/2017 5:00:00 PM (20%) Problem 1: A ball is kicked at ground level with an initial velocity of 18.5 m/s in the horizontal direction and 10.5 n the vertical direction. 33% Part (a) At what speed does the ball hit the ground in ms? 7 8 9 HOME 415161 sin0 tan() | | ( cos) cotan asin acos atan0 acotan0 sinh(0 cosh) tancotanh( Degrees O Radians END V BACKSPACE LCLEAR Submit I give upt Hints:-5 for a 0% deduction. Hints remaining:- Feedback: 0o deduction per feedback Notice we are asking for the speed, not any individual component of the velocity How is the final velocity related to the initial velocity? -Is there any acceleration in the x-direction? Then what is the final x-velocity? Is there any acceleration in the y-direction? Than what is the final If you throw something directly upwards at a velocity v, what speed does it have when it comes back down? 33% Part (b) For how long does the ball remain in the air in seconds? 3396 Part (c) what maximum height is attained by the ball in meters?Explanation / Answer
(a) At what speed does the ball hit the ground?
Vfin = Vin
= sqrt(18.5^2+10.5^2)
= 21.27 m/s (or 21.3 m/s rounded off)
(b) For how long does the ball remain in the air?
t = 2Vy/g
= 21/9.8
= 2.14 sec
(c) What maximum height is attained by the ball
hmax =Vy^2/2g
= 10.5^2/19.6
= 5.6 m
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