Unformatted text preview: speed (in m/s) was the ball thrown? (1) 12.3 (2) 14.5 (3) 16.4 (4) 10.1 (5) 7.9 Since the ball is thrown horizontally its initial velocity along the y direction, voy=0. 2
Using v2 = voy + 2a(y − yo ) with a=–g, y = 0 (at the ground) and yo = 23 , 32 or 41 m y yields the magnitude of the y component of the velocity when the ball hits the ground giving: v y = 21.23, 25.04 or 28.35 m . Knowing vy at the ground and the angle s
with which it strikes determines vx since, v
v
21.23, 25.04 or 28.35 m
s
tan θ = y ⇒ v x = y =
= 12.3, 14.5 or 16.4 m s
o
vx
tan θ
tan 60
Since there is no acceleration along the x direction this is vx everywhere including at the throw. Problem 10 A plane traveling north at 200 m/s turns and then travels south at 300 m/s (or 400 m/s, 500 m/s). The change in its velocity is: (1) 500 m/s south (2) 600 m/s south (3) 700 m/s south (4) 100 m/s south (5) 500 m/s north Δv = v f − vi = 300 m/s − ( −200 m/s ) = 500 m/s south (or 600m/s, 700...
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 Spring '14
 Physics, Acceleration, Velocity

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