How much work can be done by a 20 W motor in 5 seconds?
1 answer:
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Answer:
Maximum height, h = 10 m
Explanation:
It is given that,
Mass of golf ball, m = 45 g = 0.045 kg
The ball comes down on a tree root and bounces straight up with an initial speed of 14.0 m/s.
We need to find the height the ball will rise after the bounce. It is based on the conservation of energy such that,
h is maximum height raised by the ball
So, the ball will raised to a height of 10 meters.
at the lowest point in the trajector, the kinetic energy of the bob is 300 J.
Explanation:
The total mechanical energy of the bob at any point of its motion is given by
Where
is the kinetic energy, where
m is the mass of the bob
v is its speed
is the gravitational potential energy, where
g is the acceleration of gravity
h is the height of the bob, measured with respect to the lowest point of the trajector
In absence of friction, the total mechanical energy E remains constant. So we have:
- When the bob swings upward, the PE increases (because h increases) and the KE decreases (so the speed decreases). At the highest point in the trajector, the speed of the bob is zero (v=0), so its KE is also zero and all the mechanical energy is potential energy: U = 300 J
- When the bob swings downward, the PE decreases (because h decreases) and the KE increases (so the speed increases). At the lowest point in the trajectory, the height has become zero (h=0), so the PE is zero and all the mechanical energy is kinetic energy: KE = 300 J
Therefore, at the lowest point in the trajector, the kinetic energy of the bob is 300 J.
Learn more about kinetic energy:
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