Question

8. Sally travels by car from one city to another. She drives for 45.0 min at 30.0 m/s, 28.0 min at 25.0 m/s, and 15.0 min at 38.0 m/s, and she spends 20.0 min eating lunch and buying gas. a. Determine the average speed for the trip. b. Determine the total distance traveled.

Answer 1

Given:

v = 30 m/s , t = 45 min=2700 s

V2= 25 m/s , t2=28 min= 1680 s

V3= 38 m/s , t3 = 15 min = 900 s

v4= 0m/s , t4= 20 min= 1200s

Calculate each distance

v= d/t

d= vt

d1 = v1 t1 = 30 x 2700 = 81,000 m

d2= 25 x 1680 = 42,000 m

d3= 38 x 900 = 34200 m

Total distance = d1+d2+d3= 81000+42000+34200 = 157,200 m

Average speed = total distance / time = 157,200 / (2700 +1680 + 900 +1200 ) = 24.26 m/s

Answers:

a . 24.26 m/s

b. 157200 m