Unit 3 Slideshow 2

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

object travels.

SCALAR VS. VECTOR

SCALAR QUANTITIES

DISTANCE

TYPES OF SPEED

SPEED CALCULATIONS

DISTANCE-TIME GRAPHS

SPEED-TIME GRAPHS

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

VECTOR QUANTITIES

Any quantity that has MAGNITUDE (size) and UNITS, and DIRECTION.

Direction is symbolized by putting an ARROW above the symbol for a unit.

▪ Ex: velocity has the symbol v EXAMPLES:

▪ Velocity 25 m/s [R]

▪ Weight 50 N [D]

▪ Displacement 42 m [W33oN]

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 m EQUATION:

where:

▪ Δd = change in distance

▪ d2 = final distance

▪ d1 = initial distance

TIME is measured as the TIME DURATION between 2 events.

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

where:

▪ Δt = change in time

▪ t2 = final time

▪ t1 = initial time

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/h EQUATION:

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

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

AVERAGE SPEED (vav) A measure of the TOTAL distance over TOTAL time.

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

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!

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

Χ÷

Δv = ?

Δd = ?

Δt = ?

_____________ 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?

_____________ 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?

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

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

Do the 2 attached WORKSHEETS in your handourfor homework!!!

FASTEST CAR SSC Ultimate Aero Can travel 257 mph (0-60 in 2.7 s), costs $654,000

413.6 km/h

FASTEST LAND MAMMAL Cheetah

FASTEST ANIMALS SLOWED DOWN LINK

FASTEST GUITAR HERO PLAYER LINK

FASTEST EVERYTHING LINK

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