Two balls undergo a perfectly elastic head-on collision, with one ball initially at rest. If the incoming ball has a speed of 20
0 m/s . Part APart complete What is the final speed of the incoming ball if it is much more massive than the stationary ball?
2 answers:
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Answer:
58.5 m
Explanation:
First of all, we need to find the total time the ball takes to reach the water. This can be done by looking at the vertical motion only.
The initial vertical velocity of the ball is
where
u = 21.5 m/s is the initial speed
is the angle
Substituting,
The vertical position of the ball at time t is given by
where
h = 13.5 m is the initial heigth
is the acceleration of gravity (negative sign because it points downward)
The ball reaches the water when y = 0, so
Which gives two solutions: t = 3.27 s and t = -0.84 s. We discard the negative solution since it is meaningless.
The horizontal velocity of the ball is
And since the motion along the horizontal direction is a uniform motion, we can find the horizontal distance travelled by the ball as follows:
Using Newton's Second Law, we can find the air resistance. We know the net force is equal to mass times acceleration.