A dog runs 60 meters in 6 seconds. What is the average speed?
1 answer:
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Answer:
v = 2.18m/s
Explanation:
In order to calculate the speed of Betty and her dog you take into account the law of momentum conservation. The total momentum before Betty catches her dog must be equal to the total momentum after.
Then you have:
(1)
M: mass Betty = 40kg
m: mass of the dog = 15kg
v1o: initial speed of Betty = 3.0m/s
v2o: initial speed of the dog = 0 m/s
v: speed of both Betty and her dog = ?
You solve the equation (1) for v:
The speed fo both Betty and her dog is 2.18m/s
Answer:
Both balls hit the ground at the same time
Explanation:
Adam drops the ball from rest, so the ball just "<em>falls</em>" in vertical direction, being gravity its only acceleration, for cinematic movements we use that:
In this case we have that gravity is negative, and as Adam drops the ball,
Bob throws the ball horizontally, so the movement will be a <em>parabola</em>, we can divide into horizontal direction, and vertical direction.
But we only need to analize the vertical movement, in wich again the only acceleration is gravity, and compare it with Adam's ball. Again we have that gravity is negative, and as the initial throw is horizontal,
Finally, we have that
where
both for Adam's vertical drop, and for Bob's vertical component of the parabolic throw.
Now, if we put (the origin of the vertical coordinate), we get for both cases that
where we can clear the value for the time t, of the fall, wich will be the same in both cases.
Hence, both balls hit the ground at the same time.