Need explanation on velocity?

Question

I am still very confused. Let's say the mass of a moving object, speed, and everything else remains unchanged. The only difference being the circumference.

Lets say the circumference is 1m and has 2.5m/s velocity. If everything else is unchanged, except that i increase the circumference to 2m. Will the velocity increase twofold to 5m/s and is this practical?

Thanks for the replies. However now I get answers that contradict each other. Which is correct?

Answer 1

yes it will double ........for circle v=r*w where w is angular velocity and r is radius so if u double radius velocity will double

u need to be more specific in circular motion if u keep constant angular velocity then velocity will double if u double radius

Answer 2

You got answers which are confusing and contradicting because your question also was vague.

If the speed of the object remains but the circumference is doubled, the angular velocity (degrees or radians of the angle covered by the radius connecting the object to the centre) will become half its earlier value. Its period for each rotation will become double its earlier value.

On the other hand, if its angular velocity has to remain unchanged (constant), it has to move at double the velocity in the tangential direction. Its period of rotation will remain same.

I hope things are a little clearer now and I hope I have not added more confusion. Write to me separately if needed. Good luck.

Answer 3

If a moving object could change it's size that would have nothing to do with velocity except that in an environment where it travels threw a gas, like an atmosphere, it has resistance and will slow at a greater rate. In space if something was moving, like a satellite, and opened up to put out solar panels, and thus increase its size with no additional mass, its speed would not change. Speed is movement and it is a relationship of distance for a period of time and reflects the energy added to an object and getting work done. Size, weight, and mass( a weight for size relationship) are only brought into play when energy is used to move the object, as with thrust, and in essence is Newtons 3rd law dealing with "action" and "reaction". It could be an object hitting another, or thrust, or gravity.

So, changing a size has nothing to do with it except in the case of wind resistance or a like effect, and would slow rather than speed. In space, neither would happen. If the mass were to increase, like in space a comet picking up particles, they would have to be exactly the same speed for it to be unchanged. Slower particles impacting would take speed away and change direction. Faster particles would add speed and change direction. In an atmosphere, increases in mass would probably increase size and that would slow down the object for resistance to the gas (wind resistance) but a denser object in gravity would not fall any faster. Gravity does not change for the increase in density. A rock falls at the same rate as a canon ball. Even if they pick up rain on the way down.

It comes to my attention you might be swinging an object in a circle. If a thing goes at a certain speed it goes at that speed regardless of the size of circle. Bigger things need more energy for wind resistance to maintain the speed. Heavier things need more energy to maintain the speed. Irregardless, same speed with a larger circle takes longer to go around. You must speed up to complete the larger circle in the same time. Size with no other thing changed has nothing to do with anything ever, EXCEPT wind resistance, gas resistance, as above. Density, the mass, the weight for a specific size, is only effected by the energy in the system. In space away from all gravity sources, energy is put into an object to swing around. The mass of that object and the speed to get up to will determine how much energy is needed.

Answer 4

No, velocity is independent of size and mass. The larger sphere would still have a velocity of 2.5m/s. Size is the most irelevant factor in these situations, until you get really advanced and start factoring air resistance.

Answer 5

VELOCITY = DISPLACEMENT/TIME
VELOCITY MEANS DISPLACEMENT OF BODY WITH RESPECT TO TIME.