Missing Parts
Here are the formulae to work out the thinking distance and the braking distance for a car traveling at V miles per hour.
Thinking distance = V feet
[tex]\text{Braking distance = }\dfrac{V^2}{20}$ feet[/tex]
(a) A car is traveling at 70 miles per hour. What is the total stopping distance for this car? feet
(b) A different car is traveling so that its braking distance is 125 feet. How fast is the car traveling? miles per hour
Answer:
(a)2520 feet
(b)50mph
Step-by-step explanation:
Total Stopping Distance = Thinking Distance + Braking Distance
Given that for a car traveling at V miles per hour:
Thinking distance = V feet
[tex]\text{Braking distance = }\dfrac{V^2}{20}$ feet[/tex]
We have:
[tex]\text{Total Stopping Distance=} (V+\dfrac{V^2}{20})$ feet[/tex]
(a)V=70 miles per hour
[tex]\text{Total Stopping Distance=} 70+\dfrac{70^2}{20}$=2520 feet[/tex]
The total stopping distance for a car traveling at 70 miles per hour is 2520 feet.
(b)
Braking Distance = 125 feet
[tex]\text{Braking distance = }\dfrac{V^2}{20}$ feet[/tex]
Therefore:
[tex]\dfrac{V^2}{20}=125\\\\V^2=125\times 20\\V^2=2500\\V^2=50^2\\V=50$ miles per hour[/tex]
A car with a braking distance of 125 feet is traveling at a speed of 50mph.
