Answer:
The answer is the 1st one
According to the conservation of mechanical energy, the kinetic energy just before the ball strikes the ground is equal to the potential energy just before it fell.
Therefore, we can say KE = PE
We know that PE = m·g·h
Which means KE = m·g·h
We can solve for h:
h = KE / m·g
= 20 / (0.15 · 9.8)
= 13.6m
The correct answer is: the ball has fallen from a height of 13.6m.
They have the same velocity because their displacements (shortest line from point A to point B, which is a straight line) are the same and they meet at the same time.
Please ignore my comment -- mass is not needed, here is how to solve it. pls do the math
at bottom box has only kinetic energy
ke = (1/2)mv^2
v = initial velocity
moving up until rest work done = Fs
F = kinetic fiction force = uN = umg x cos(a)
s = distance travel = h/sin(a)
h = height at top
a = slope angle
u = kinetic fiction
work = Fs = umgh x cot(a)
ke = work (use all ke to do work)
(1/2)mv^2 = umgh x cot(a)
u = (1/2)v^2 x tan (a) / gh
The longer the time between the arrival of the P-wave and S-wave, the <u>farther away</u> is the epicenter.
<h3>
What is epicenter and the relation between P-wave and S-wave?</h3>
- The point on the earth's surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture begins is said to be epicenter.
- There are two types of waves during earthquakes, they are:
- P - wave
- S - wave
- Each seismograph records the times when the first (P waves) and second (S waves) seismic waves arrive.
- From the graph, through the information, scientists can determine how fast the waves are traveling.
- The longer the time between the arrival of the P-wave and S-wave, the farther away is the epicenter.
Hence, Option B is the correct answer.
Learn more about epicenter,
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