question with ez physics problem

[Garuda]

Originally posted by: neonerd

Originally posted by: Skoorb
5.725 is the answer

what'd u use to get it?

He used the same equation you did.

You need to get your conventions straight at the start of the problem. If gravity is negative (or if it's positive but you have a minus sign in front of it), then your initial velocity is also negative.

In physics, it's all about setting the problem up right. It's all about thinking the math through and keeping your conventions consistent. Just remember that, and you'll do well.

 

[neonerd]

Originally posted by: Garuda

Originally posted by: neonerd

Originally posted by: Skoorb
5.725 is the answer

what'd u use to get it?

He used the same equation you did.

You need to get your conventions straight at the start of the problem. If gravity is negative (or if it's positive but you have a minus sign in front of it), then your initial velocity is also negative.

In physics, it's all about setting the problem up right. It's all about thinking the math through and keeping your conventions consistent. Just remember that, and you'll do well.

kind of why i got confused...my physics teacher gave us some equation, and told us that the negative factor for gravity and the rest of everything has been worked into the equation already....idk

 

[MikeMike]

Originally posted by: neonerd

Originally posted by: Garuda

Originally posted by: neonerd

Originally posted by: Skoorb
5.725 is the answer

what'd u use to get it?

He used the same equation you did.

You need to get your conventions straight at the start of the problem. If gravity is negative (or if it's positive but you have a minus sign in front of it), then your initial velocity is also negative.

In physics, it's all about setting the problem up right. It's all about thinking the math through and keeping your conventions consistent. Just remember that, and you'll do well.

kind of why i got confused...my physics teacher gave us some equation, and told us that the negative factor for gravity and the rest of everything has been worked into the equation already....idk

yup, if gravity was negative, then you wouldnt have to make the initial velocity negative, it would all cancel out in the end.

MIKE

 

[daveshel]

Originally posted by: neonerd

Originally posted by: mugs

Originally posted by: daveshel
I think that is a terminal velocity guestion.

He's like 15, I don't think they deal with that in high school physics, at least not this early in the year.

i'm taking 11th grade physics in 10th grade, lol

11th grade was the only formal physics I ever had - and I didn't do very well, either.

 

[mugs]

Originally posted by: neonerd
kind of why i got confused...my physics teacher gave us some equation, and told us that the negative factor for gravity and the rest of everything has been worked into the equation already....idk

Knowing the equation might help you if you just want to pass a test, but knowing how the equation works, why it works, and where it came from are more important to actually understanding physics. I think that's why most people suck at physics, they either don't or can't understand those things.

 

[Mo0o]

The original equations d=Di + Vi(t) + (1/2)A(t)^2. The only time you want to have your acceleration as negative is when you're moving in the opposite direction of the acceleration. So if you shoot something UP, then g should be negative.

 

[neonerd]

Originally posted by: Mo0o
The original equations d=Di + Vi(t) + (1/2)A(t)^2. The only time you want to have your acceleration as negative is when you're moving in the opposite direction of the acceleration. So if you shoot something UP, then g should be negative.

ooooo...so it's positive because it's basically increasing speed rather than slowing it down. Was what i did for if the pebble was going up? hence the negative, because it's slowing down the pebble. i think i understand it now, thanks

 

[ThisIsMatt]

5.72625

 

[neonerd]

thx everyone, and as mugs said, i understand it now

 

[Fenixgoon]

Originally posted by: Skoorb
5.725 is the answer

i got 5.726 as well.


y= y0 + v0(t) + 1/2 at^2

y = 0 + 9(.5) + (.5)(.25)(9.8)

boo yea for physics, which i'm currently taking

 

[Chronoshock]

This thread mades baby einstein cry