1. A ball is launched from ground level and hits the ground again after an elaps

Question

1. A ball is launched from ground level and hits the ground again after an elapsed time of 3.7 seconds and after traveling a horizontal distance of 69 m. The only force acting on the ball is gravity.

What is the initial y-component of the ball's velocity?

A) Vy,initialVyinitial = 36.3 m/s

B) Vy,initialVyinitial = 72.6 m/s

C) Vy,initialVyinitial = 30.1 m/s

D) Vy,initialVyinitial = 24.1 m/s

E) Vy,initialVyinitial = 18.1 m/s

2. A football is kicked across a level field. The ball spends 4.7 seconds in the air and lands a distance XX = 59 meters from the point where it was kicked. The initial speed of the ball is V0V0. You should ignore air resistance.

Suppose the ball was kicked with the same initial angle but with twice the initial speed. How far from the kicker would the ball land?

A) Xnew=2XXnew2X

B) Xnew=4XXnew4X

C) Xnew=2X

PLEASE EXPLAIN AND SHOW WORK!

Explanation / Answer

Range u^2 sin 2theta /g = R

u^2 sin 2 theta = gR

Total time of flight = 2usin theta/g = 3.7

u sin theta= 3.7g/2 = 1.85g = 1.85*9.8 = 18.13 m/s2

Answer is D as u sin theta is vertical component of velocity

2)

Range is related to initial speed as R = u^2

hence, new range is (2u)^2 = 4u^2

=B) Xnew=4XXnew4X

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