Hw problem..physics?

Question

a particle moves along an axis with an intitial position of 7cm.

After 0.035 sec. the particles position is 1cm. ...determine the avg. velocity annnnd the avg. speed of the particle during this time interval

Answer 1

First, start off with the formula, which we know as velocity = change in distance/time: v=d/t.   (To find the change in distance, you do distance final - distance initial)

So we substitute in the values we know, which are the change in distance and time, giving us (1-7)/.035. This gives us that the velocity is -171.428571 cm/s. The speed would be the same thing, without the negative.

The negative shows direction, which is the difference between velocity and speed.  

Answer 2

Velocity = V = (D2 - D1)/T

where

D2 = final position of particle = 1 cm (given)

D1 = initial position of particle = 7 cm (given)

T = time = 0.035 sec.

Substituting appropriate values,

V = (1 - 7)/0.035 = -6/0.035

V = -171.43 cm/sec.

NOTE the negative value attached to the velocity. It simply means that the particle is moving towards the origin.