Help on these physics questions please.

Question

A) An airplane travels 2100 km at a speed of 1000 km/h. It then encounters a headwind that slows it to 800 km/h for the next 1300km. What was the average speed of the plane for this trip.

B) Two locomotives approach each other on parallel tracks. Each has a speed of 120 km/h with respect to the earth. If they are initially 8.5 km apart, how long will it be before they pass each other?

Answer 1

2100 km at a speed of 1000 km / h = 2.1 hours.

1300 km at a speed of 800 km / h = 1.6 hours.

3400 km in a time of 3.7 hours yields an average speed of 920 km / h.

The relative velocity of the two locomotives is 240 km / h. At this relative speed they will meet in .035 hours or about 2.1 minutes.

Answer 2

b.)

4.25 km till passing point.

120km/h

speed = distance over time

speed x distance = time

120 x 4.25= 510

510 divided by 60 = 8.5 mins