Is enough information given to solve this problem?

Page 2 - Seeking answers? Join the AnandTech community: where nearly half-a-million members share solutions and discuss the latest tech.

TheCanuck

Senior member
Apr 28, 2003
373
0
0
Go here for some simple formulas in velocity: Velocity

Angle, friction, and gravity are irrelevant. Resistance is futile.

Solve for v, then a, then figure out vf, then calc your final distance -- less than 20 more than 12 ;)
 

dullard

Elite Member
May 21, 2001
26,024
4,650
126
Originally posted by: mugs
I agree that it's possible, but why would you need/want to know the angle of the plane? Isn't the acceleration all you need to solve the problem?
1) The OP stated that he could do the rest of the work with the angle.
2) It is really not any more work to find the angle.
3) Sometimes doing it all rather than taking a shortcut helps you learn far better than taking the shortcut.

So yes, you could do it without the angle. My question is are people here in this thread that bad at physics that they can't find the angle? It isn't like we are talking hours here. We are talking seconds worth of work.
 

Specop 007

Diamond Member
Jan 31, 2005
9,454
0
0
Originally posted by: RGUN
Why would you waste time figuring out the angle? Just avoid that and setup your axis so that the ball travels parallel to x, therefore the angle is 0 in your local coordinate system. Now its just a matter of finding out the acceleration and then carrying that through for 27s

This guy is obviously way better at math then I am.
 

scorpmatt

Diamond Member
Feb 8, 2001
7,040
97
91
Originally posted by: dullard
Originally posted by: mugs
I agree that it's possible, but why would you need/want to know the angle of the plane? Isn't the acceleration all you need to solve the problem?
It isn't like we are talking hours here. We are talking seconds worth of work.

27 seconds to be exact. ;)
 

Savij

Diamond Member
Nov 12, 2001
4,233
0
71
Originally posted by: scorpmatt
Originally posted by: dullard
Originally posted by: mugs
I agree that it's possible, but why would you need/want to know the angle of the plane? Isn't the acceleration all you need to solve the problem?
It isn't like we are talking hours here. We are talking seconds worth of work.

27 seconds to be exact. ;)


How do you know the work without the mass of the ball?
 

Savij

Diamond Member
Nov 12, 2001
4,233
0
71
Originally posted by: TheCanuck
Go here for some simple formulas in velocity: Velocity

Angle, friction, and gravity are irrelevant. Resistance is futile.

Solve for v, then a, then figure out vf, then calc your final distance -- less than 20 more than 12 ;)

I'm runing through my numbers and getting something higher than that...
 

TuxDave

Lifer
Oct 8, 2002
10,571
3
71
Assumptions needed:
1) EDIT NM you don't need this assumption.
2) No friction
3) Constant acceleration due to gravity

Given the above you can solve it using kinematic equations.
 

slpaulson

Diamond Member
Jun 5, 2000
4,414
14
81
Originally posted by: Savij
Originally posted by: TheCanuck
Go here for some simple formulas in velocity: Velocity

Angle, friction, and gravity are irrelevant. Resistance is futile.

Solve for v, then a, then figure out vf, then calc your final distance -- less than 20 more than 12 ;)

I'm runing through my numbers and getting something higher than that...


Me too, much higher.
Although I am very rusty and could have done something dumb.
 

2Xtreme21

Diamond Member
Jun 13, 2004
7,044
0
0
Originally posted by: cRazYdood
Originally posted by: Savij
Originally posted by: TheCanuck
Go here for some simple formulas in velocity: Velocity

Angle, friction, and gravity are irrelevant. Resistance is futile.

Solve for v, then a, then figure out vf, then calc your final distance -- less than 20 more than 12 ;)

I'm runing through my numbers and getting something higher than that...


Me too, much higher.
Although I am very rusty and could have done something dumb.

Guys, I appreciate all the help muchly. Came up with 36 on my first try and it's the correct answer. :) Thank you thank you thank you!
 

Savij

Diamond Member
Nov 12, 2001
4,233
0
71
Originally posted by: cRazYdood
Originally posted by: Savij
Originally posted by: TheCanuck
Go here for some simple formulas in velocity: Velocity

Angle, friction, and gravity are irrelevant. Resistance is futile.

Solve for v, then a, then figure out vf, then calc your final distance -- less than 20 more than 12 ;)

I'm runing through my numbers and getting something higher than that...


Me too, much higher.
Although I am very rusty and could have done something dumb.

You forgot to divide by 2?

 

slpaulson

Diamond Member
Jun 5, 2000
4,414
14
81
Originally posted by: 2Xtreme21
Originally posted by: cRazYdood
Originally posted by: Savij
Originally posted by: TheCanuck
Go here for some simple formulas in velocity: Velocity

Angle, friction, and gravity are irrelevant. Resistance is futile.

Solve for v, then a, then figure out vf, then calc your final distance -- less than 20 more than 12 ;)

I'm runing through my numbers and getting something higher than that...


Me too, much higher.
Although I am very rusty and could have done something dumb.

Guys, I appreciate all the help muchly. Came up with 36 on my first try and it's the correct answer. :) Thank you thank you thank you!


Yeah I was wrong in saying it was much higher. I did something dumb and wrote down a as 81/8 instead of 8/81. I didn't think that seemed quite right...
 

dullard

Elite Member
May 21, 2001
26,024
4,650
126
Originally posted by: 2Xtreme21
Guys, I appreciate all the help muchly. Came up with 36 on my first try and it's the correct answer. :) Thank you thank you thank you!
Close. 36 m is correct. But 36 isn't. I know, I'm picky.
 

sash1

Diamond Member
Jul 20, 2001
8,896
1
0
Originally posted by: dullard
Originally posted by: 2Xtreme21
Guys, I appreciate all the help muchly. Came up with 36 on my first try and it's the correct answer. :) Thank you thank you thank you!
Close. 36 m is correct. But 36 isn't. I know, I'm picky.

lol. but if his physics teacher at lives gives a damn then 36 is wrong. no units = wtf?
 

2Xtreme21

Diamond Member
Jun 13, 2004
7,044
0
0
Ok, there's a box where you can type a number in and after the box is "m" so I figure I have my bases covered in that respect. :p
 

scorpmatt

Diamond Member
Feb 8, 2001
7,040
97
91
Originally posted by: Savij
Originally posted by: scorpmatt
Originally posted by: dullard
Originally posted by: mugs
I agree that it's possible, but why would you need/want to know the angle of the plane? Isn't the acceleration all you need to solve the problem?
It isn't like we are talking hours here. We are talking seconds worth of work.

27 seconds to be exact. ;)


How do you know the work without the mass of the ball?

27 seconds is already given
 

Savij

Diamond Member
Nov 12, 2001
4,233
0
71
Originally posted by: scorpmatt
Originally posted by: Savij
Originally posted by: scorpmatt
Originally posted by: dullard
Originally posted by: mugs
I agree that it's possible, but why would you need/want to know the angle of the plane? Isn't the acceleration all you need to solve the problem?
It isn't like we are talking hours here. We are talking seconds worth of work.

27 seconds to be exact. ;)


How do you know the work without the mass of the ball?

27 seconds is already given


Work is the dot product of force and displacement right? I'm a little rusty on this stuff now.

Force is mass time acceleration. We can find acceleration and use that to find displacement, but how do we get the mass....it's not so funny when I have to explain it.
 

Schmide

Diamond Member
Mar 7, 2002
5,745
1,036
126
To solve such a problem you need 2 of the following

Forces, Scale/Positions/Displacement, Time

The only thing given in that problem is time. No solution.

Some may say the the force of gravity is given, but you can't determine how it is applied to the sphere without knowing the angle of the ramp. So no you don't have the force.
 

goodoptics

Platinum Member
Aug 18, 2000
2,652
0
0
Originally posted by: Schmide
To solve such a problem you need 2 of the following

Forces, Scale/Positions/Displacement, Time

The only thing given in that problem is time. No solution.

Some may say the the force of gravity is given, but you can't determine how it is applied to the sphere without knowing the angle of the ramp. So no you don't have the force.

Time, position, initial velocity were given, and someone has already said that the answer is 36m.
 

Schmide

Diamond Member
Mar 7, 2002
5,745
1,036
126
My bad I read it as 4 minutes 9 second, not 4 meters in 9 seconds.

I'm a dumbass