Achild throws a ball with an initial speed of 8.00 m/s at an angle of 40.0° above the horizontal. the ball leaves her hand 1.00 m above the ground and experience negligible air resistance. (a) how far from where the child is standing does the ball hit the ground?

7.5 m

Explanation:

= initial speed of the ball = 8 m/s

= angle of launch = 40° deg

Consider the motion along the vertical direction :

= initial velocity along vertical direction = = 8 Sin40 = 5.14 m/s

= acceleration along vertical direction = - 9.8 m/s²

= time of travel

= vertical displacement = - 1 m

Using the kinematics equation

= 1.22 sec

Consider the motion along the horizontal direction :

= initial velocity along horizontal direction = = 8 Cos40 = 6.13 m/s

= acceleration along vertical direction = 0 m/s²

= time of travel = 1.22 sec

= horizontal displacement = ?

Using the kinematics equation

= 7.5 m

the correct choice is a .

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