# How many constraints are there when the particle is moving in a plane

1. Jun 13, 2010

### roshan2004

How many constraints are there when the particle is moving in a plane and on three dimensional space and what are they?

2. Jun 14, 2010

### arildno

Re: Constraints

1. How many spatial quantities must be specified in order to uniquely determine the particle's position as a function of time?

2. How many equations exist that relate those spatial quantities to each other?

1. tells you the degrees of freedom of the system, 2. the constraints upon the system.

3. Jun 14, 2010

### roshan2004

Re: Constraints

For number one,obviously there are three spatial quantities for describing the particle's position for the particle in three dimension and two for the particle in plane. However I am sorry that I couldn't figure out the second one.

4. Jun 14, 2010

### arildno

Re: Constraints

Suppose the plane the particle is to move on lies in a 3-D world.

How many constraints are then put on the particle's motions?

5. Jun 14, 2010

### roshan2004

Re: Constraints

I guess it is two

6. Jun 14, 2010

### arildno

Re: Constraints

Why?

How many equations in x,y and z are needed to specify a particular plane?

7. Jun 14, 2010

### roshan2004

Re: Constraints

Three

8. Jun 15, 2010

### arildno

Re: Constraints

Do you even know how to specify a plane with the help of equation(s)??

9. Jun 15, 2010

### roshan2004

Re: Constraints

in the form of ax+by+cz=0

10. Jun 15, 2010

### arildno

Re: Constraints

And how many equations is that expression??

11. Jun 15, 2010

### roshan2004

Re: Constraints

only one