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Sun 30 Sep, 2007 09:20 pm
Ok, here goes:
"Bob measures the motion of a toy car. It starts 4m east of his reference point and moves 4m east, 6m west, and 9m east. It takes 20 s top complete all these moves."
And it tells me to:
a. find the total distance travelled; which I think is 19m.
b. find the final position of the car; which I think is 11m.
c. Find the total displacement of the car. Which I totally am lost and don't know what to do.
d. Find the car's average speed; which, same as above.
e. Find the car's average velocity; which, ditto.
Can somebody please explain the difference between average speed and average velocity? And what does TOTAL displacement mean? Thanks so much for your help!
speed is a scaler quantity like lets say 50 km/h, velocity is a vector which has a quantity and a direction : 50 km/h north-east , the total displacement is initial position minus final position, note that a scalar quantity is always positive while a vectoriel quantity may be negative since it shows the direction aswell....i just read the last two lines so i dont know if your answers are correct
A and B look right to me.
Displacement should be the difference between starting position and ending position.
Speed will be total distance divided by time.
Vector will be displacement divided by time.
C - The displacement of the car can be found by drawing a straight line from its starting point to its ending point. Therefore, its displacement will be 4 - 6 + 9 = 7m
D- To find the car's average speed, divide the distance travelled by the time it takes to travel such a distance. 19/20 = 0.95 m/s
E- To find the car's average velocity you must do two things: divide the displacement by the time it takes to acheive such a displacement, and find the direction travelled. 7/20 = 0.35 m/s East.
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