# No idea (velocity)

1. Sep 16, 2007

### wiskeywiz

1. The problem statement, all variables and given/known data
car moving 12.0m/sec eastward on straight road. inside car, bug is flying eastward at 2.0m/s relative to the car. how fast is the bug moving relative to the road? repeat for the bug moving westward.

2. Relevant equations

3. The attempt at a solution

i assume the westward movement will be a negative ratio

2. Sep 16, 2007

### atavistic

You know how relative velocity works?

Its like this:

V1(Relative velocity of body 'a' wrt to body 'b') = V2(Velocity of body 'a' wrt ground) -
V3(Velocity of body 'b' wrt ground)

Yes the westward movement will be -ve quantity if u take the eastward motion of car as +ve.

Last edited: Sep 16, 2007
3. Sep 16, 2007

### wiskeywiz

what about average acceleration? is that distance/time?

4. Sep 16, 2007

### mezarashi

Change in displacement over time is velocity. Changes in velocity over time is acceleration.

Average acceleration is the average acceleration over a period of time, say t1 (10.30am) and t2 (10.32am). Then if the velocity v1 at t1 was 40km/hr and the velocity v2 at time t2 was 30km/hr, the average acceleration would be:

(v2-v1) divided by (t2-t1) = (-10km/hr) per (2 mins) = -5 km/hr per min
which is interpreted as a slow down of 5km/hr in velocity every minute, over the past 2 minutes.