Uniform Motion Round Trip

OBJECTIVESOLVE PROBLEMS

INVOLVING UNIFORM MOTION

Uniform Motion Round Trip

Uniform Motion

Uniform motion is when an object moves without changing its speed.

Solving Word Problems

1. Draw a sketch 2. Identify unknowns3. Assign variable4. Make a chart5. Write and solve an equation

Equation for Motion Round Trip

Distance for object one equals the distance for object two.

Example

A ski lift carried Maria up a slope at the rate of 6 km/h, and she skied back down parallel to the lift at 34 km/h. The round trip took 30 min.

How long did she ski?

Draw a sketchDraw a Diagram

Assign Variables

Let t = Maria’s skiing time

Notice that 30 min = ½ hour

Make a ChartSKIINGSKIING RATERATE TIMETIME DISTANCEDISTANCE

UPUP

DOWNDOWN

30 t 6 30 t6

34tt34

34 6 30t t

34 180 6t t 6t 6t

40t 40

180

40

20 14 min 4 min40 2

t

Maria skied for 4.5 minutes downhill.She went up the lift for 30-4.5 or 25.5 minutes.How far did she ski? Oh ohSince km/h is in hours 4.5min=__hrsSmall to big divide. 4.5/60=3/40hours3/40hr x 34km/h =2 and 11/20km

Try This

Kathy hiked up a hill at 4 km/h and back down at 6km/h. His total hiking time was 3 hours.

How long did the trip up hill take him?

Make a ChartHIKINGHIKING RATERATE TIMETIME DISTANCEDISTANCE

UPUP

DOWNDOWN

4(3 )t4

6t6

3 t

t

6 4(3 )t t

4t 4t10 12t

10 12

10 10

t

6 11 1 12min

5 5t hr

10 12t

Kathy hiked down the hill for 1 hr 12 min.How long did the trip up take her? Since She went up the hill for 3 hrs - 1 hr 12min 1 hr 48 min minutes