# Homework Help: Find average acceleration from two given velocities each at a given ti

1. Apr 26, 2013

### tylertwh

The velocity of an object at t=0 seconds is 40 m/s directed due North. The velocity of the same object at t=5 seconds is 30 m/s directed due east.

Find the magnitude of the average acceleration of the object over the time interval from t=0 to t=5 seconds.

Also, show the direction of the average acceleration.

So... I am not quite sure how to even approach this problem. I originally tried it and did it with Pythagorean Theorem, but my answer was incorrect.

The answer I got using Pythagorean Theorem was 50 m/s at 36.9 East of North.

2. Apr 26, 2013

### haruspex

Judging from your diagrams, you did a vector addition of the two velocities. You want the change involved in going from one velocity to the other. What operation should you use?

3. Apr 26, 2013

### Staff: Mentor

First consider the component of acceleration in the north-south direction. What is the change in the velocity component in this direction? From this, what is the acceleration (don't forget to divide by the time)?

Now do the same thing for the east-west direction.