SCIENCE 1206 – MOTIONUnit 3 Slideshow 2

Motion is a measure of CHANGES IN POSITION, as marked by HOW FAR, HOW LONG, and HOW

FAST an object travels.

SPEED RECORDS!!!

FASTEST PRODUCTION CAR LINK

FASTEST LAND MAMMAL LINK

FASTEST WING SPEED LINK

FASTEST ANIMALS SLOWED DOWN LINK

FASTEST RUBIX CUBE LINK

FASTEST HANDS LINK

FASTEST EVERYTHING LINK

TOPICS OUTLINE

SCALAR VS. VECTOR

SCALAR QUANTITIES DISTANCE TYPES OF SPEED SPEED CALCULATIONS DISTANCE-TIME GRAPHS SPEED-TIME GRAPHS

SCALAR VS. VECTOR QUANTITIES

SCALAR QUANTITIES Any quantity that has MAGNITUDE (size)

and UNITS, but NO DIRECTION. EXAMPLES:▪ Time 2.5 h▪ Speed 25 m/s▪ Mass 5.0 kg▪ Distance 42 m

SCALAR VS. VECTOR QUANTITIES

VECTOR QUANTITIES Any quantity that has MAGNITUDE (size)

and UNITS, and DIRECTION. Direction is symbolized by putting an

ARROW above the symbol for a quantity.

▪ Ex: velocity has the symbol v EXAMPLES:▪ Velocity 25 m/s [R]▪ Weight 50 N [D]▪ Displacement 42 m [W33oN]

DISTANCE (symbol Δd)

Δ, greek letter “delta,” means “change in”

Distance is a measure of the TOTAL TRAVEL of an object, regardless of direction.

Units are metres, m, OR kilometres, km.

1 km = 1000 mEQUATION:

Δd = d2 – d1 where:▪ Δd = change in distance ▪ d2 = final distance

▪ d1 = initial distance

TIME (symbol Δt)

TIME is measured as the TIME DURATION between 2 events.

Units are seconds, s, OR hours, h.1 h = 3600 sEQUATION:

Δt = t2 – t1 where:▪ Δt = change in time ▪ t2 = final time

▪ t1 = initial time

SPEED (symbol Δv)

SPEED is a measure of the distance of an object per unit time.

Units are m/s, OR km/h.1 m/s = 3.6 km/hEQUATION:

Δv = Δd Δt where:

▪ Δv = change in speed, in m/s or km/h▪ Δd = change in distance, in m or

km▪ Δt = change in time, in s or h

THREE TYPES OF SPEED

CONSTANT SPEED (Δv) AKA UNIFORM MOTION When an object is travelling at constant

speed, it is travelling at the SAME SPEED for a period of time.

EXAMPLE▪ Cruise control▪ Speed of light in air is c = 3.00 x 108 m/s

THREE TYPES OF SPEED

AVERAGE SPEED (vav) A measure of the TOTAL distance over TOTAL time. Vav = dTOTAL = dT

tTOTAL = tT

INSTANTANEOUS SPEED (vinst) A measure of the speed at a particular MOMENT in

time. Instantaneous speed is NOT affected by an object’s

PREVIOUS SPEED or HOW LONG is has been moving. EXAMPLE:▪ Speedometer▪ Police Radar Gun

PROBLEM-SOLVING SKILLS

When doing physics problems, follow the following guidelines: READ PROBLEM (i.e., don’t just pick out

the numbers)! Write GIVENS and UNKNOWNS. Write EQUATION FIRST, rearranging if

necessary. Plug in numbers and solve for answer. Write answer in SIG FIGS, with UNITS,

and CIRCLE it!

REARRANGING THE SPEED EQUATION

Since the SPEED equation has only 3 VARIABLES, you can easily rearrange it using the following helpful “triangle.”

Δv

Δd

ΔtΧ÷

Δv = ?

Δd = ?

Δt = ?

SAMPLE PROBLEM 1

_____________ wants to ride his bike from Corner Brook to Deer Lake, a distance of 45 km. If he only has 0.50 h to get there, what speed does he have to travel?

SAMPLE PROBLEM 2

_____________ wants to ride her bike from Corner Brook to Deer Lake, a distance of 45 km. Unlike ____________, she calculated her average speed to be 20.0 km/h. How long will it take her to get there?

SAMPLE PROBLEM 3

______________ is travelling for a triathlon and ran at a speed of 15 km/h for 2.0 h. What distance has he travelled?

SAMPLE PROBLEM 4

On her scooter, ______________ travels 12 km in 2.5 h and then 15 km in 35.5 minutes. What is her average speed?

HOMEWORK!!!

Do the Worksheets 7 and 8 (page 20-21)in your handout for homework!!!

the truck?

vcar = 90 km/h = 25 m/svtruck = 50 km/h = 14 m/sd = 100 mt for car to reach truck = ?

dtruck + 100 = dcar

vt + 100 = vt14t + 100 = 25t100 = 11t9 = tt= 9 s