- #1
Jigen
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Just finished an exam. One problem is bothering me and I want to be certain if it's right.
What is the maximum velocity of an object dropped from a 20 m cliff?
Assume no air friction and gravity is 10 m/s/s.
None given, but I assume v=gt is relevant.
15 m/s.
My reasoning was that if after 1s, the object fell 10m at 10m/s,
and after 2s, the object has fallen 30m (10m + 20m) at 20m/s (10m/s + 10m/s),
then I can divide the 2nd speed increment in half to determine speed at 20m fall (10m/s + 5m/s).
I tried using equations before answering 15.
v=gt by itself can't work without t (t was not given).
d=1/2gt^2 tells me the object fell for 2s, but that doesn't seem right (it would have traveled 30m).
Assuming t=2s is right, v = 10m/s/s * 2s = 20m/s.
So which is right: 15 or 20?
Homework Statement
What is the maximum velocity of an object dropped from a 20 m cliff?
Assume no air friction and gravity is 10 m/s/s.
Homework Equations
None given, but I assume v=gt is relevant.
The Attempt at a Solution
15 m/s.
My reasoning was that if after 1s, the object fell 10m at 10m/s,
and after 2s, the object has fallen 30m (10m + 20m) at 20m/s (10m/s + 10m/s),
then I can divide the 2nd speed increment in half to determine speed at 20m fall (10m/s + 5m/s).
I tried using equations before answering 15.
v=gt by itself can't work without t (t was not given).
d=1/2gt^2 tells me the object fell for 2s, but that doesn't seem right (it would have traveled 30m).
Assuming t=2s is right, v = 10m/s/s * 2s = 20m/s.
So which is right: 15 or 20?