# Help with simple vector graph

1. Oct 27, 2011

### iamBevan

Hi guys - i need some help with a really simple problem. I've just started doing physics in college, and I've had a homework question that just doesn't work out for me (I also have the answers).

A particle moves in a straight line with a constant velocity of 5m/s for 2 seconds. It then moves with a constant acceleration of -2m/s^2 for 8 seconds. Sketch a velocity-time graph for the interval of 10 seconds and find:

a) the final velocity
b)the total distance covered by the particle
c)the increase in displacement of the particle

i'm getting -10m/s for a - then 44.5m for b.

Could someone tell me if I'm atleast heading in the right direction? (no pun intended)

2. Oct 27, 2011

### PeterO

If the initial velocity is 5 [given] and the final velocity is -10 [your calculation] then the change is -15.

AN acceleration of -2 for 8 seconds does not give -15 .

3. Oct 27, 2011

### iamBevan

If I know my vector is -2m/s^2 then - how will I work out the final velocity of that vector from that?

4. Oct 27, 2011

### PeterO

Why did you say your vector was -2 m/s2?

Surely you meant your acceleration was -2 m/s2.

5. Oct 27, 2011

### iamBevan

Isn't the vector describing an acceleration?

6. Oct 27, 2011

### PeterO

Both velocity and acceleration are vectors

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