Everything Science Grade 10

21.3 CHAPTER 21. MOTION IN ONE DIMENSION

a. What is the distance you have walked?

b. What is your final displacement?

c. Is displacement a vector or a scalar? Give a reason for your answer.

More practice video solutions or help at http://www.everythingscience.co.za

(1.) 009j (2.) 009k

Speed and velocity ESAGW

DEFINITION: Average speed

Average speed is thedistance(D) travelled divided by the time (∆t) taken

for the journey.

Quantity: average speed (vav) Unit name: metre per second Unit

symbol: m·s−^1

DEFINITION: Average velocity

Average velocity is thechange in positionof a body divided by the time it

took for the displacement to occur.

Quantity: average velocity (~vav) Unit name: metre per second Unit

symbol: m·s−^1

Before moving on review the difference between distance and displacement. Sometimes

the average speed can be a very big number while the average velocity is zero. See

video:

at http://www.everythingscience.co.za

Average velocity is the rate of change of position. It tells us how much an object’s position

changes per unit of time. Velocity is a vector. We use the symbol~vavfor average velocity.

396 Physics: Mechanics