Explanation:
a) The height of the ball h with respect to the reference line is
so its initial gravitational potential energy is
b) To find the speed of the ball at the reference point, let's use the conservation law of energy:
We know that the initial kinetic energy as well as its final gravitational potential energy
are zero so we can write the conservation law as
Note that the mass gets cancelled out and then we solve for the velocity v as
Answer:
The answer would be 420 m/s
Explanation:
Look in attachment ⬇
I Hope this Helps!!!
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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