w=f[z] Posted June 21, 2007 Share Posted June 21, 2007 Here is a little question; Let's say you are driving along in your car on a cold-autumn day. You have a passenger in the center of the back seat that is holding a helium-filled balloon in front of them by the string. You make a sharp left turn around a bend in the road. Which way does the balloon move relative to the car? (Justify your answer.) Cheers, w=f[z] P.S. I'm still really new here, so my apologies if this has already been discussed. Link to comment Share on other sites More sharing options...
YT2095 Posted June 21, 2007 Share Posted June 21, 2007 it`ll move to the right the same as you do. Justification: preservation of Inertial forces. Link to comment Share on other sites More sharing options...
insane_alien Posted June 21, 2007 Share Posted June 21, 2007 it'll move to the left. justification, buoyancy. the air is heavier than the balloon. if it was a air filled balloon i would agree with YT Link to comment Share on other sites More sharing options...
w=f[z] Posted June 21, 2007 Author Share Posted June 21, 2007 it`ll move to the right the same as you do. Justification: preservation of Inertial forces. Hi YT, This problem has been known to confuse physicists a time or two. You might want to reconsider.... Cheers Link to comment Share on other sites More sharing options...
YT2095 Posted June 21, 2007 Share Posted June 21, 2007 IA, it makes no difference what the balloon is filled with as long it has MASS, it`s subject to the same force Link to comment Share on other sites More sharing options...
w=f[z] Posted June 21, 2007 Author Share Posted June 21, 2007 it'll move to the right. justification, buoyancy. the air is heavier than the balloon. if it was a air filled balloon i would agree with YT Did you mean left IA? Link to comment Share on other sites More sharing options...
YT2095 Posted June 21, 2007 Share Posted June 21, 2007 he meant Left so did I damn our rotten mistyping keyboards! Link to comment Share on other sites More sharing options...
w=f[z] Posted June 21, 2007 Author Share Posted June 21, 2007 Just so we're all clear on this... If we turn left (as in the problem), and say we have a ball resting on the dashboard, the ball will move right relative to the car. Yes? Cheers Link to comment Share on other sites More sharing options...
YT2095 Posted June 21, 2007 Share Posted June 21, 2007 naah it`ll go left also, sure it will, it`s got He gas in it although I`ve no idea HOW you`ll make it "Rest" on the dashboard???? Link to comment Share on other sites More sharing options...
timo Posted June 21, 2007 Share Posted June 21, 2007 A helium-filled balloon resting on the dashboard? It won't move relative to the car at all since it's squeezed too tightly between the dashboard and the windshield . Link to comment Share on other sites More sharing options...
w=f[z] Posted June 21, 2007 Author Share Posted June 21, 2007 ;344715']Just so we're all clear on this...If we turn left (as in the problem)' date=' and say we have a ball resting on the dashboard, the ball will move right relative to the car. Yes? Cheers[/quote'] Note here I mean ball - not balloon. Perhaps I should have said coin or something else of that nature. D'oh! Link to comment Share on other sites More sharing options...
insane_alien Posted June 21, 2007 Share Posted June 21, 2007 ;344712']Did you mean left[/i'] IA? i said left. /me shiftily draws attention away from the editted notification. A, it makes no difference what the balloon is filled with as long it has MASS, it`s subject to the same force yeah but if it is less dense than aire then it'll move left, if it is more dense then it will move right Link to comment Share on other sites More sharing options...
YT2095 Posted June 21, 2007 Share Posted June 21, 2007 ok, NOW I`m officially confused Link to comment Share on other sites More sharing options...
insane_alien Posted June 21, 2007 Share Posted June 21, 2007 okay, take it to the extreme situation. you have a tank half filled with water(half empty if you're one of those people) with a little boat floating on it. it just so happens this tank is on the end of a centrifuge. whe you start of the water will be level and the boat is on top. as it spins faster and faster, the water will rotate so he surface is nearly perpendicular to the ground. the boat will still be floating on he surface as if nothing has happened. Link to comment Share on other sites More sharing options...
richard Posted June 21, 2007 Share Posted June 21, 2007 Right, inertia. Link to comment Share on other sites More sharing options...
D H Posted June 21, 2007 Share Posted June 21, 2007 IA is right, it moves to the left. This left/right business is making it apparent that SFN members may have some dyslexic tendencies. To avoid confusion, why don't ya'll talk about what happens to a helium-filled balloon in a moving car that suddenly comes to a stop? Link to comment Share on other sites More sharing options...
insane_alien Posted June 21, 2007 Share Posted June 21, 2007 tried it, it goes left. yes i specifically went out and bought a helium balloon to check my hypothesis. Link to comment Share on other sites More sharing options...
Klaynos Posted June 21, 2007 Share Posted June 21, 2007 What if it's a convertible with the roof down? Link to comment Share on other sites More sharing options...
D H Posted June 21, 2007 Share Posted June 21, 2007 I noticed this effect when one of my kids was holding a balloon in the car. The balloon went forward when I accelerated and backward when I applied the brakes. Link to comment Share on other sites More sharing options...
w=f[z] Posted June 21, 2007 Author Share Posted June 21, 2007 What if it's a convertible with the roof down? Bingo! Read the original post carefully and see if you spot my subtle hint.... Cheers Link to comment Share on other sites More sharing options...
Klaynos Posted June 21, 2007 Share Posted June 21, 2007 ;344789']Bingo! Read the original post carefully and see if you spot my subtle hint.... Cheers Cold autumn day so you'd have the car nicely sealed up Link to comment Share on other sites More sharing options...
swansont Posted June 22, 2007 Share Posted June 22, 2007 i_a is right, and D H's point is well-taken. 1-D is better than 2-D. Newton's first law: an object that's in motion remains in motion, and all that. Driver hits the brakes, and everthing has the tendency to continue to move forward. "Everything" includes the air in the car. Since that is more dense than the He-balloon, the balloon will actually move backward, i.e. in the direction of the acceleration, because it is displaced by the air. Do it in a vacuum, and it will behave as you would expect for a generic mass. (But do it with a remote-controlled car) Link to comment Share on other sites More sharing options...
Rasori Posted June 24, 2007 Share Posted June 24, 2007 I think you'd be hard-pressed to have a helium-filled balloon in a vacuum. Link to comment Share on other sites More sharing options...
J.C.MacSwell Posted June 24, 2007 Share Posted June 24, 2007 I think you'd be hard-pressed to have a helium-filled balloon in a vacuum. It would of course roll around on the floor. Link to comment Share on other sites More sharing options...
Rasori Posted June 25, 2007 Share Posted June 25, 2007 It would of course roll around on the floor. The matter is the balloon: the pressure difference between the vacuum and the inside of the balloon would not last. The pressures would attempt to equalize, eventually ending in the popping of the balloon. Link to comment Share on other sites More sharing options...
![w=f[z]](https://www.scienceforums.net/uploads/set_resources_1/84c1e40ea0e759e3f1505eb1788ddf3c_default_photo.png)
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now