newtonian..i know basic...

[SaintJude]

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A ball is shot horizontally off of the top of the building if acceleration due to gravity were twice its present value, what would the maximum distance of the ball be if all the other factors remained the same.

Why is the answer (in white) "1/2 the distance? "

It's so frustrating but simple newtonian mechanisms is still getting me..

 

[pfaction]

y=10a(tsq)
Time will decrease. Horizontal distance depends on time.

Example
100m = 5(tsq)
tsq = rad20
vox(rad20)

100m = 10(tsq)
vox(rad10)

HALF!

I hope I'm doing this right!

 

[SaintJude]

Well, Kaplan said a = dv/ t .

What I didn't realize is that delta v would be the same?

So I didn't apply that equation.

 

[HollowSuperet36]

Hypothetical a ball 10m off ground in air one sec. Double g and in air one half sec. Horizontal distance is equal to velocity times time in air.

 

[jevo]

if you use one of the kinematics:

v^2=v0^2 + 2ax , then solve for x (assume v0^2 = 0 since the ball started from rest)

x = (v^2) / (2/a)

Now you know that X (height) is inversely proportional to acceleration at 1/(2a).

And now if you double the acceleration, x becomes 1/(4a) which is half of its original value.

Right?

 

[MedPR]

A ball is shot horizontally off of the top of the building if acceleration due to gravity were twice its present value, what would the maximum distance of the ball be if all the other factors remained the same.

Why is the answer (in white) "1/2 the distance? "

It's so frustrating but simple newtonian mechanisms is still getting me..

I'm not getting 1/2 the distance.. What's wrong with this?



h=1/2gt^2.

So say height is 10 and you are on earth. 10=5t^2. t=1.4s.

Now double the gravity. 10=10t^2. t=1.

 

[Class1P]

I hate projectile motion so flipping much. I can understand extremely complex biological and biochemical pathways but kinematics still kills me.

 

[MT Headed]

A ball is shot horizontally off of the top of the building if acceleration due to gravity were twice its present value, what would the maximum distance of the ball be if all the other factors remained the same.

Why is the answer "1/2 the distance?"

It isn't. This answer is wrong. Where did you get it?

In the Y direction:
y = (1/2) a t^2
t = sqrt(2y/a)

In the X direction:
x = v t
x = v sqrt(2y/a)

THEREFORE
if you keep v (the horizontal velocity) the same, and you keep y (the height) the same, and you double "a", you will reduce x by the square root of 2, or a factor of 1.4.

Acceleration would have to quadruple in order to reduce the distance by 1/2.

 

[MedPR]

I'm not getting 1/2 the distance.. What's wrong with this?



h=1/2gt^2.

So say height is 10 and you are on earth. 10=5t^2. t=1.4s.

Now double the gravity. 10=10t^2. t=1.

It isn't. This answer is wrong. Where did you get it?

In the Y direction:
y = (1/2) a t^2
t = sqrt(2y/a)

In the X direction:
x = v t
x = v sqrt(2y/a)

THEREFORE
if you keep v (the horizontal velocity) the same, and you keep y (the height) the same, and you double "a", you will reduce x by the square root of 2, or a factor of 1.4.

Acceleration would have to quadruple in order to reduce the distance by 1/2.

So my reasoning (quoted above) is right? Thank goodness, my MCAT is TOMORROW and I kind of freaked out a little.

 

[chiddler]

So my reasoning (quoted above) is right? Thank goodness, my MCAT is TOMORROW and I kind of freaked out a little.

good luck!

 

[EnginrTheFuture]

Edit: realized it was shot horizontally after typing up a long response. BUMMER

Good luck tomorrow anyway!

 

[MedPR]

good luck!

Thanks 🙂

 

[pfaction]

Good luck medpr!!!

 

[411309]

It isn't. This answer is wrong. Where did you get it?

In the Y direction:
y = (1/2) a t^2
t = sqrt(2y/a)

In the X direction:
x = v t
x = v sqrt(2y/a)

THEREFORE
if you keep v (the horizontal velocity) the same, and you keep y (the height) the same, and you double "a", you will reduce x by the square root of 2, or a factor of 1.4.

Acceleration would have to quadruple in order to reduce the distance by 1/2.

I would def agree with this. I dunno why other people are using different equations. Theres no way it could be "1/2"

 

[4563728]

I know this thread is kind of old, but to double check the answer is not 1/2 but 1/(sqrt 2) ?