In: Physics
Let A be the sum of the last four digits and let B be the last digit of your 8-digit student ID. (Example: For 20245347, A = 19 and B = 7) On a road trip, a driver achieved an average speed of (48.0+A) km/h for the first 86.0 km and an average speed of (43.0-B) km/h for the remaining 54.0 km. What was her average speed (in km/h) for the entire trip? Round your final answer to three significant figures.
t1 = 86/(48+A) = 86/67 = 1.28 hr
t2 = 54/(43-B) = 54/36 = 1.5 hr
total time t = t1+t2 = 2.78 hr
total distance = 86+54 = 140 km
total avg velocity = 140/2.78 = 50 km/hr