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The accompanying table shows time-to-speed data for a particular car accelerating from rest

to 120 mph. How far had the car traveled by the time it reached this speed? (Use trapezoids
to estimate the area under the velocity curve. Notice that intervals vary in length.)
Speed change
Zero to
20 mph
30 mph
40 mph
50 mph
60 mph
70 mph
80 mph
90 mph
100 mph
110 mph
120 mph
Time (sec)
2.2
3.5
5.1
6.8
9.0
11.7
14.5
18.1
23.0
28.9
40.1

User Chakri
by
8.6k points

1 Answer

3 votes

By the time the car reached a speed of 120 mph, it had traveled an estimated distance of 2965 miles.

To estimate the distance traveled by the car when it reached a speed of 120 mph, we can use trapezoids to approximate the area under the velocity curve.

First, let's calculate the time intervals between each speed change. We can do this by subtracting the time at one speed from the time at the previous speed:

Interval 1: 3.5 sec - 2.2 sec = 1.3 sec

Interval 2: 5.1 sec - 3.5 sec = 1.6 sec

Interval 3: 6.8 sec - 5.1 sec = 1.7 sec

Interval 4: 9.0 sec - 6.8 sec = 2.2 sec

Interval 5: 11.7 sec - 9.0 sec = 2.7 sec

Interval 6: 14.5 sec - 11.7 sec = 2.8 sec

Interval 7: 18.1 sec - 14.5 sec = 3.6 sec

Interval 8: 23.0 sec - 18.1 sec = 4.9 sec

Interval 9: 28.9 sec - 23.0 sec = 5.9 sec

Interval 10: 40.1 sec - 28.9 sec = 11.2 sec

Now, we can calculate the average speed for each interval by taking the sum of the speeds at the start and end of the interval and dividing by 2:

Average speed for interval 1: (0 mph + 20 mph) / 2 = 10 mph

Average speed for interval 2: (20 mph + 30 mph) / 2 = 25 mph

Average speed for interval 3: (30 mph + 40 mph) / 2 = 35 mph

Average speed for interval 4: (40 mph + 50 mph) / 2 = 45 mph

Average speed for interval 5: (50 mph + 60 mph) / 2 = 55 mph

Average speed for interval 6: (60 mph + 70 mph) / 2 = 65 mph

Average speed for interval 7: (70 mph + 80 mph) / 2 = 75 mph

Average speed for interval 8: (80 mph + 90 mph) / 2 = 85 mph

Average speed for interval 9: (90 mph + 100 mph) / 2 = 95 mph

Average speed for interval 10: (100 mph + 110 mph) / 2 = 105 mph

Next, we can calculate the distance traveled during each interval by multiplying the average speed by the time interval:

Distance for interval 1: 10 mph * 1.3 sec = 13 miles

Distance for interval 2: 25 mph * 1.6 sec = 40 miles

Distance for interval 3: 35 mph * 1.7 sec = 59.5 miles

Distance for interval 4: 45 mph * 2.2 sec = 99 miles

Distance for interval 5: 55 mph * 2.7 sec = 148.5 miles

Distance for interval 6: 65 mph * 2.8 sec = 182 miles

Distance for interval 7: 75 mph * 3.6 sec = 270 miles

Distance for interval 8: 85 mph * 4.9 sec = 416.5 miles

Distance for interval 9: 95 mph * 5.9 sec = 560.5 miles

Distance for interval 10: 105 mph * 11.2 sec = 1176 miles

Finally, we can sum up the distances for each interval to get the total distance traveled by the car:

Total distance = 13 miles + 40 miles + 59.5 miles + 99 miles + 148.5 miles + 182 miles + 270 miles + 416.5 miles + 560.5 miles + 1176 miles

Total distance = 2965 miles

Therefore, by the time the car reached a speed of 120 mph, it had traveled an estimated distance of 2965 miles.

User Vijay Chouhan
by
8.3k points