kinematics

[chitrangda]

Choose one of the right answers:-

 

A particle is thrown up vertically from a vehicle moving in a small path(with respect to cart).If we neglect dimensions of cart:

 

1) The particle will land back in the cart

 

2) The particle will land outside the circular path

 

3) The particle will follow a parabolic path

 

4) As soon as the particle is released it's acceleration becomes zero.

[Bignose]

Bookworm, the server was down for a time, so people may not have been able to post to help you.

 

That said, this is the homework help session, and one of the major rules here is that the forum member will help, but you have to show us what you have done to date to solve this on your own. What ideas have you tried? Any equations you think are appropriate?

[Anjruu]

A cart moving in a circular path, and a particle is thrown upward from the cart, right?

 

From whose frame of reference? Outside the whole system? In that case I think it is choice 3, because the velocity vector at any point in circular motion is tangent to the circle, and the particle no longer has any centripetal acceleration keeping it in the circle, so it is 'free' to follow the velocity tangent. This means that it has both horizontal and vertical (from the upward throw) components of motion and nothing else, resulting in parabolic motion. Does that sounds correct? I've probably forgotten something...

 

EDIT

However, that means that choice 2 is also correct, because if it follows a parabolic path, it has velocity along x, which will take it outside the circle, so my answer can't be correct, because it would make two answers correct. It can't be 4, because there is acceleration downward due to gravity, which leaves 1. But I can't see how that would be...

[chitrangda]

I am completely clueless about this question.

 

So,which option is correct?

[Anjruu]

Ahehe, I'm not sure. Lets try again. Its not 4, there is acceleration due to gravity. Its not 3, because, if it were 3, it must also be 2, which discounts 3. It might be 2, because 2 does not force 3 like 3 forces 2. It cannot be 1, because that would imply the existence of a centrifugal force making the particle go in a circle. Therefore, the answer is 2. Hows that? Does that make sense?

[Severian]

Choose one of the right answers:-

 

A particle is thrown up vertically from a vehicle moving in a small path(with respect to cart).If we neglect dimensions of cart:

 

I am not sure I am understanding the question. Are you meaning that the cart is moving in a circle? Or is this path straight?

 

It is very pertinant to the question because if it is moving in a straight line then (presumably) it is not accelerating' date=' whereas if it is turning it is accelerating.

 

1) The particle will land back in the cart

 

This will only happen if the cart is not accelerating. So this is only true if the cart is moving with constant velocity.

 

2) The particle will land outside the circular path

 

This is the answer which made me think the cart is moving in a circle. If it is, then this is true. If it isn't, I am not even sure what this statement is trying to say!

 

3) The particle will follow a parabolic path

 

Relative to the ground, this statement is always true. Relative to the cart, it is never true (unless you count an infinitely thin parabola).

 

4) As soon as the particle is released it's acceleration becomes zero.

 

This is always false. Gravity is acting on it so it will accelerate.