Kinematics: IntroPhysic 11

What is kinematics? area of Physics Is the branch of mechanics concerned

with motion without reference to force or mass

Scalar verses vector: Scalar: a measurement only having

magnitude or size Ex: 55 km/hr

25 kg88 mL

Vector: a measurement that has magnitude and direction

Ex: 55 km/hr SW 125 m N

Distance:• is a scalar

quantity which refers to "how much ground an object has covered" during its motion.

• What was this person’s distance?

Start/finish

Position (position vector): Symbol: Location of an object at a given time based off

a point of reference Position vector: starts from the origin of a

coordinate system

d

Displacement: The change or difference between the

final position and the initial position of an object

Symbol: ∆d ∆d = positionfinal – positioninital

∆d = df – di

How are distance and displacement different?

start

finish

45 m

175 m

Time and time interval: Usually the time at which an event

begins is designated 0 (zero) seconds. Time interval: the time elapsed between

two instants of time

∆t= tfinal – tinital

What is the time interval for A to B?

A to D?

C to D?

Speed: Speed = distance__

time

describes how fast something is moving. It is a scalar quantity (does NOT indicate direction)

Example:• While on vacation, Karen traveled a total

distance of 440 km. Her trip took 5 hours. What was her average speed?

speed= d / t s = 440km / 5hr

s = 88km/hr

Average Velocity A vector quantity that describes how fast

and in what direction an object is moving (displacement/time interval)

“rate of change of position”

Vave = ∆d or df - di ∆t tf - ti

Example 1:• A helicopter flies 158 km due south from the

airport to a rescue site and it arrives at the site 26.0 mins later, what is the helicopter’s velocity in km/hr?

ti = 0, tf =26min, di =0km, df=158 km S, Vave=? Convert min to hrs: 26.0 min x1hour =0.433 hr

60min Vave = ∆d

∆t= 158km – 0km 0.433hr – 0 hr

= 367 km/hr

Example 2:• The space shuttle Endeavor is

launched to altitude of 500 000 m North of the surface of the earth. The shuttle travels at an average rate of 700 m/s. How long will it take for Endeavor to reach its orbit?

ti = 0, tf =?, di =0m, df=500 000m N, Vave= 700m/s Finish on board!

Practise: Pg 39# 1, 2 Pg 40 # a, b Pg 41# 1, 2 Pg 45# 2,3