[04:11] Distance, time, and speed

SpeedAPRIL11TH, 2018

Objective

◦Iwillbeabletoanalyzegraphsandunderstand

therelationshipbetweendistance,time,and

speed

Speed,v◦Thedistance anobjectmovesinacertainlengthoftime

Speedisa quantity

Representedbyanumberandunits(i.e.km/h,m/s,cm/s)SIunit:metres/second(m/s)

Constantspeed:

Changingspeed:

Constantspeed:

Changingspeed:

◦Whenanobjecttravelsthesamedistanceforeachtimeinterval

Constantspeed:

Changingspeed:

◦Whenanobjecttravelsthesamedistanceforeachtimeinterval

Whenanobjecttravelsadifferentdistanceforeachtimeinterval

Graphingdistance,time,andspeed

Distance-timegraph

Distance-TimeGraph

Slope=m =!"#$!%&

='(')

'(')

='?'?

Distance-TimeGraph

Slope=m =!"#$!%&

='(')

'(')

='+',

=?

Use the slope to calculate average speed!

Slope=m =!"#$!%&

='(')

'(')

='+',

=vavg

Averagespeed◦Thedistancetravelledbyanobjectisdividedbythetimeittakestotravelthatdistance

𝑣avg = '+',

Averagespeed=+"#,0&1$,!02$33$+,4,03,"5$$306#$+

Example

◦Determinetheaveragespeedoftheobjectfrom4.5sto7.5s.

m =!"#$!%&

='(')

=(78(")78)"

= 88

=________m/s

Lookatonepoint(instant)onthegraph

Whatistheslope(speed)atthatpoint?

Thisiscalled…

Instantaneousspeed

◦Thespeedataspecificinstant oftime

◦Useaverysmalltimeinterval

Whenthespeedisconstant…

Whatdoyounoticeabouttherelationshipbetweenvinst andvavg?

Whenthespeedisconstant…

vinst isequal tovavgforthattime

interval

vinst = vavg

Homework◦Reading◦P.220-223

◦Questions:Showyourwork!◦Yesterday:P.219#5-7,11,18◦Speed:P.219#9,15-16

CommentaryActivity

1. Designaracebetweentwo

runners

2. Plotadistance-time graph

3. Writeacommentary

4. Tomorrow:Actouttheskit

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