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.

- omnomnom

- jamiebookeater

See more answers at brainly.com

At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga.
Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus.
Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Get this expert

answer on brainly

SEE EXPERT ANSWER

Get your **free** account and access **expert** answers to this

and **thousands** of other questions

- anonymous

\[mgh = \frac{ 1 }{ 2 }mv ^{2}\]

- anonymous

you can subtract the mass from both sides which shows that everything falls at the same rate

- anonymous

you know what g is

Looking for something else?

Not the answer you are looking for? Search for more explanations.

## More answers

- omnomnom

Gravity?

- anonymous

yes

- anonymous

so if you plug in the velovity and solve for h which is the height

- anonymous

is this for conservation of energy

- omnomnom

No this is only for the height of the building

- anonymous

The formula I gave you is the conservation of energy

- anonymous

In this case \(g\) is the gravitational acceleration we talked about in the previous problem.

- anonymous

You cannot solve this with kinematics there are too many unknowns

- anonymous

What do you mean you can't solve it with kinematics?

- anonymous

Yeah I guess you could solve for time in the acceleration then plug it in the average velocity.

- anonymous

I was talking about the \(g\) in your formula.

- omnomnom

??

- anonymous

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.

- anonymous

that is why I was asking

- anonymous

Last question was a 'kinematic' one so maybe it must be kinematics.

- anonymous

acceleration of gravity = velocity final minus velocity inital divided by time.

- anonymous

@omnomnom Have you talked about work or energy in your class yet?

- anonymous

Like potential energy or kinetic energy?

- omnomnom

No whats work?

- anonymous

It is something you will learn in the future, most likely.

- anonymous

yes solve for time then plug into \[\frac{ d }{ t }=\frac{ v _{f}+v _{i} }{ 2 }\]

- anonymous

conservation is so much easier to solve

- omnomnom

it confused me though
the first equstion

- omnomnom

equation*

- anonymous

Don't worry about it.

- anonymous

@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.

- omnomnom

oh okay so what equation do i use.... is is\[d =Vi( t)+ a \frac{ 1 }{ 2 }(t^2) \]

- anonymous

You can't use that equation until you find time though.

- omnomnom

Oh yeah >.<

- anonymous

\[a=\frac{ v _{f}-v _{i} }{ t }\]

- anonymous

you know a and both velocities

- omnomnom

But we need the time :( Cant i just quess the answer?

- anonymous

Yes, \(a\) is the same as last time... \(9.81m/s^2\)

- anonymous

velocity initial is 0

- anonymous

You are not supposed to guess, because there is already a way to find the answer.

- omnomnom

but...... Whats the way ?

- anonymous

t=49/9.81

- omnomnom

answer is 5

- anonymous

yes 5 seconds

- anonymous

then plug in the time into your equation and find x

- omnomnom

oh hold on

- omnomnom

i got 49 m/s

- anonymous

that is the velocity

- omnomnom

so we change the equation now?

- anonymous

you want the height of the building

- omnomnom

yeah

- anonymous

x=1/2t(vfinal-vinital)

- omnomnom

122.5 meters?

- anonymous

yes

- omnomnom

thank you :D

- anonymous

do you understand the kinematic equations

- omnomnom

The first one ? NO the others Yes

- anonymous

http://www.physicsclassroom.com/

- anonymous

this is a helpfull tool

- omnomnom

oh kay thank you :D

Looking for something else?

Not the answer you are looking for? Search for more explanations.