Physics: A Car Moves in a Straight Line
Problem: A car moves in a straight line at 16 m/s for 9 miles, then at 30.0 m/s for another 9 miles.
V1 = 16 m/s, D1 = 9 miles = 14,484.06 m, V2 = 30 m/s, D2 = 9 miles = 14,484.06 m
(a) Is the car’s average speed less than, greater than, or equal to 23 m/s?
(b) Calculate the car’s average speed.
Solution: In order to solve a), we must first solve for b).
Find the time it takes to travel each interval.
T1 = D1 / V1 = 905.25 s
T2 = D2 / V2 = 482.802 s
Now that we have the time during each interval, we can find the total time by adding them up:
Ttot = T1 + T2 = 1388.06 s
Now, to get the average speed, we just have to divide the total distance by the total time:
Vavg = (D1 + D2) / Ttot = 20.87 m/s
Answer: Vavg = 20.87 m/s which is less than 23 m/s