A stopwatch measure the stone's trajectory time from the top of the cliff to the bottom to be 2.5s. What is the height of the cliff? ( Assuming gravitational acceleration is 9.8m/s^2)
A) 25m
B)19m
C)12m
2007-07-18 18:22:23 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Physics
The height of the cliff is indeterminable because you were not told how tall the thrower is.
The time to hit the bottom of the cliff would be a calculation of the height of the cliff PLUS THE DISTANCE FROM THE GROUND AT THE TOP OF THE CLIFF TO THE THROWER'S HAND.
EDIT:
re: I must disagree withpearlsawme's logic...
There is a lot of room for errors in measurement
Just because 25m is less than 30 meters does not make it a correct answer.
If we were told that one of the options is the actual height of the cliff, then A would be correct. Since we do not know this for a fact, the assumption is not SCIENTIFICALLY SOUND.
.
2007-07-18 19:39:13 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The horizontal velocity makes no difference. Only the vertical acceleration matters. For constant acceleration, s = .5*a*t^2. In this case, a = g. None of your answers fit.
2007-07-18 18:29:43 · answer #2 · answered by gp4rts 7 · 0⤊ 0⤋
Height = .5 g t^2 = 30.625.m
Due to friction, the time given is little more than the time if there is no friction
The height will be little less than 30.625 m
All the answers are less than 30.625.
It seems reasonable to select 25m.
The answer is A.
2007-07-18 22:37:15 · answer #3 · answered by Pearlsawme 7 · 0⤊ 0⤋
only the gravitational acceleration matters.
h=1/2g*t^2
h=30.625
so... D) Your teacher gave you no correct answers
2007-07-18 18:53:08 · answer #4 · answered by El Conquistador 2 · 0⤊ 0⤋
are you asking merely because you are interested? or is this a homework question?
2007-07-18 18:24:52 · answer #5 · answered by hot.turkey 5 · 0⤊ 0⤋