# Homework Help: Motion in One-Dimension

1. Sep 9, 2007

### luna02525

1. The problem statement, all variables and given/known data

Two objects A and B are connected by a rigid rod that has a length 35 m. The objects slide along perpendicular guide rails. If A slides to the left with a constant speed 35.2379 m/s along the x-axis, find the velocity of B along the y-axis when the rod makes an angle 27* with the x-axis. Answer in units of m/s

2. Relevant equations

I'm not even sure.

3. The attempt at a solution

I attempted to find the velocity using the equation:

$$\vec{Ay}$$=$$\vec{A}$$sin$$\Theta$$

so,

$$\vec{Ay}$$=35sin(27*)

$$\vec{Ay}$$= 15.890 m/s

This, however, was not correct and I really am confused about what even would be correct or how I should go about solving the problem.

Thank you in advance for any help or information (or direction...).

2. Sep 9, 2007

### bel

Since $$x^2+y^2=35$$, then $$\frac{y}{x}=tan(\psi)$$. Then you can differentiate both sides of that by the time t. You know the required angle, and you know $$\frac{dx}{dt}$$ as well.

3. Sep 9, 2007

### luna02525

so,

$$y=xtan\Theta$$

$$\frac{dy}{dt}=\frac{dx}{dt}tan27$$

$$\frac{dy}{dt}=35.2379*tan27$$ ?

4. Sep 9, 2007

### bel

No, you have to make use of the relation $$x^2+y^2=35$$ as well and treat $$\psi$$ as a function of time $$t$$.

5. Sep 9, 2007

### Astronuc

Staff Emeritus
I think one wants - $$x^2+y^2=35^2$$

6. Sep 9, 2007

### bel

Oh right, it is the square of 35, silly me, how could I have forgotten? I apologise.