Question

joe cool drives to see his girlfriend who attends another college.
(a) the 156 km trip takes 2.0 h. what was the average speed for the trip?
\\( \square \\) km/h
(b) the return trip over the same route takes 3.0 h because of heavy traffic. what is the average speed for the return trip?
\\( \square \\) km/h
(c) what is the average speed for the entire trip?
\\( \square \\) km/h

Explanation:

Step1: Calculate average speed for part (a)

Use the formula \(v=\frac{d}{t}\), where \(d = 156\) km and \(t=2.0\) h.
\(v_{1}=\frac{156}{2.0}\)

Step2: Calculate average speed for part (b)

Use the formula \(v=\frac{d}{t}\), where \(d = 156\) km and \(t = 3.0\) h.
\(v_{2}=\frac{156}{3.0}\)

Step3: Calculate average speed for part (c)

Total distance \(D=156 + 156=312\) km. Total time \(T=2.0+3.0 = 5.0\) h. Use the formula \(v=\frac{D}{T}\).
\(v=\frac{312}{5.0}\)

Answer:

(a) \(78\) km/h
(b) \(52\) km/h
(c) \(62.4\) km/h