3. When you threw the ball upward at 40 m/s, how much time would have
1 answer:
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The hang time of the ball is 4.08 s
Explanation:
The ball is in free fall motion: this means that it is acted upon gravity only, so its acceleration is the acceleration of gravity,
downward (the negative sign refers to the downward direction).
Since this is a uniformly accelerated motion, we can solve the problem by using the following suvat equation:
where
v is the final velocity
u is the initial velocity
a is the acceleration
t is the time
First we calculate the time it takes for the ball to reach the maximum height, where the velocity is zero:
v = 0
Substituting:
u = +20 m/s
we find t
The motion of the ball is symmetrical, so the total time of flight is just twice the time needed to reach the maximum height, therefore:
Learn more about free fall:
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Answer:
D) 11 m/s
Explanation:
We have to calculate the velocity of the hot dog with respect to the observer still outside the train. This velocity will be given by:
where
is the velocity of the train (towards right)
is the velocity of the man (towards right)
is the velocity of the hot-dog (towards left, so we put a negative sign)
By replacing the numbers into the equation, we find
and the positive sign means the velocity is toward right.