Average speed = (total distance covered) / (total time to cover the distance) .
Total distance = (80 + 50 + 40) = 170 km
Total time = (1 + 0.5 + 0.5) = 2 hours
Average speed = (170 km) / (2 hrs) = 85 km/hr .
Ill save you all the math steps, but here is the answer! <span>102.25m I took that physics exam 3 days ago! So if you need the steps just ask Ill insert them in!</span>
It's Photoelectric Effect, I just a test with this same question. I am not good for explaining exactly how, but I was right.