# Homework Help: Kinematics / vectors

1. Jan 10, 2009

### bikerboi92

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

A particle has an initial horizontal velocity of 2.6 m/s and an initial upward velocity of 3.5 m/s. It is then given a horizontal acceleration of 1.3 m/s^2 and a downward acceleration of 1.2 m/s^2.

What is its speed after 2.2 s?

What is the direction of its velocity at this time with respect to the horizontal (answer between -180º and +180º)

2. Relevant equations

all kinematic equations

3. The attempt at a solution

i'm lost on this one

2. Jan 10, 2009

### LowlyPion

Welcome to PF.

Acceleration is a vector. Velocity is a vector.

You can treat the horizontal and vertical components separately.

You know for instance that Final Velocity is equal to Initial velocity + acceleration times time. Vf = Vi + a*t

Once you determine your components of the resulting Velocity ... combine ... you're done.

3. Jan 10, 2009

### NBAJam100

You are going to end up with 2 final velocities, one in the x and one in the y.

So to find the direction from the positive x axis, take triangles into consideration. You'll have an x component and a y component so you can easily solve for the direction with respect to the horizontal.

4. Jan 10, 2009

### bikerboi92

thanks, i solved and got the right answer