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omnomnom
Group Title
A stone is dropped from the roof of a tall building. A person measures the speed of the stone to be 49 m/sec when it hits the ground. The height of the building is closest to:
Select one:
a. 24 meters.
b. 49 meters.
c. 122 meters.
d. 245 meters.
 2 years ago
 2 years ago
omnomnom Group Title
A stone is dropped from the roof of a tall building. A person measures the speed of the stone to be 49 m/sec when it hits the ground. The height of the building is closest to: Select one: a. 24 meters. b. 49 meters. c. 122 meters. d. 245 meters.
 2 years ago
 2 years ago

This Question is Closed

Decart Group TitleBest ResponseYou've already chosen the best response.2
\[mgh = \frac{ 1 }{ 2 }mv ^{2}\]
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
you can subtract the mass from both sides which shows that everything falls at the same rate
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
you know what g is
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
so if you plug in the velovity and solve for h which is the height
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
is this for conservation of energy
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
No this is only for the height of the building
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
The formula I gave you is the conservation of energy
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
In this case \(g\) is the gravitational acceleration we talked about in the previous problem.
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
You cannot solve this with kinematics there are too many unknowns
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
What do you mean you can't solve it with kinematics?
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
Yeah I guess you could solve for time in the acceleration then plug it in the average velocity.
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
I was talking about the \(g\) in your formula.
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
Though technically speaking, depending on whether they are on the 'energy' part or the 'kinematic' part of the course decides which method they should use.
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
that is why I was asking
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
Last question was a 'kinematic' one so maybe it must be kinematics.
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
acceleration of gravity = velocity final minus velocity inital divided by time.
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
@omnomnom Have you talked about work or energy in your class yet?
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
Like potential energy or kinetic energy?
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
No whats work?
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
It is something you will learn in the future, most likely.
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
yes solve for time then plug into \[\frac{ d }{ t }=\frac{ v _{f}+v _{i} }{ 2 }\]
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
conservation is so much easier to solve
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
it confused me though the first equstion
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
Don't worry about it.
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
@omnomnom This is a two step problem. First you want to figure out how long it took to fall. Then you want to use that to figure out how far it fell.
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
oh okay so what equation do i use.... is is\[d =Vi( t)+ a \frac{ 1 }{ 2 }(t^2) \]
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
You can't use that equation until you find time though.
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
Oh yeah >.<
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
\[a=\frac{ v _{f}v _{i} }{ t }\]
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
you know a and both velocities
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
But we need the time :( Cant i just quess the answer?
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
Yes, \(a\) is the same as last time... \(9.81m/s^2\)
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
velocity initial is 0
 2 years ago

wio Group TitleBest ResponseYou've already chosen the best response.0
You are not supposed to guess, because there is already a way to find the answer.
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
but...... Whats the way ?
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
answer is 5
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
yes 5 seconds
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
then plug in the time into your equation and find x
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
oh hold on
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
i got 49 m/s
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
that is the velocity
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
so we change the equation now?
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
you want the height of the building
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
x=1/2t(vfinalvinital)
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
122.5 meters?
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
thank you :D
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
do you understand the kinematic equations
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
The first one ? NO the others Yes
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
http://www.physicsclassroom.com/
 2 years ago

Decart Group TitleBest ResponseYou've already chosen the best response.2
this is a helpfull tool
 2 years ago

omnomnom Group TitleBest ResponseYou've already chosen the best response.0
oh kay thank you :D
 2 years ago
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