Uniform Motion Round
Trip
OBJECTIVE
SOLVE PROBLEMS
INVOLVING UNIFORM
MOTION

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

Solving Word Problems
 1. Draw a sketch
 2. Identify unknowns
 3. Assign variable

4. Make a chart

5. Write and solve an equation

Equation for Motion
Round Trip

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 Diagram
Draw a sketch

Assign Variables
 Let t = Maria’s skiing time
 Notice that 30 min =
½ hour

SKIING
Make a Chart
RATE TIME DISTANCE
UP
DOWN
6
34
30
 t
  t
 t 34 t

34 t
   t

34 t

6 t

180 6

6 t t
40 t

180
40 40 t

20
4 min 4 min
40

1
2

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 oh
Since km/h is in hours 4.5min=__hrs
Small to big divide.
4.5/60=3/40hours
3/40hr 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?

HIKING
Make a Chart
RATE TIME DISTANCE
UP
DOWN
4
6
3
 t
4(3
 t ) t 6 t

6 t

4(3
 t )
10 t

12

4 t

4 t
10 t

12
10 t

12
10 10 t
 
1
1
5 5
 hr

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