# Homework Help: Vector Kinematics

1. Aug 28, 2010

### tdcamp

A particle starts from the origin at t = 0 with an initial velocity of 5.0 m/s along the positive x axis. If the acceleration is (-4.9 + 2.9 ) m/s2, determine the velocity and position of the particle at the moment it reaches its maximum x coordinate.

velocity i m/s + j m/s
position i m + j m

i am completely lost on this.

2. Aug 28, 2010

### s3a

When the height of release of a projectile equals the height of landing, the optimum angle is 45 degrees. The optimum angle basically is the angle at which you launch a projectile to cover the greatest horizontal distance. The velocity, V, in its components is Vx = Vcos45deg and Vy = Vsin45deg, in this case. Also i means horizontal and j means vertical.

3. Aug 28, 2010

### tdcamp

thanks for the help but thats not it. the I hat for V in the answer is 0. i can't determine the J hat or position vectors however.

4. Aug 29, 2010

### s3a

Sorry your question is a little unclear. Is the acceleration in i and j? Is the vertical height unknown? Is the vertical velocity unknown or just not mentioned?

5. Aug 29, 2010

### tdcamp

That's what I was thinking too. It seams as if there is not enough information present to solve the equation.

6. Aug 29, 2010

### s3a

It seems so but in case I'm wrong, in the future: you need either 3 known variables for one component or two known variables per two components then combine the equations.