A ball starts at 10m East. The ball rolls 60 m West in 9 seconds. Then the ball rolls East for 85 m in 8 seconds. What was the velocity of the ball for the whole trip?

The speed of the ball was 30.7 km/h.

Explanation:

To determine the speed at which the ball moves, it is necessary to make the sum of the distance traveled and the time it takes to travel that distance. Thus, since it first rolls 60 meters in 9 seconds, and then rolls another 85 meters in 8 seconds in the opposite direction, in total it rolls 145 meters in 17 seconds.

Thus, since 145/17 is equal to 8.52, its speed is 8.52 meters per second. Now, since a minute has 60 seconds, and an hour has 60 minutes, to determine the speed in meters per hour you must multiply 8.52 x 60 x 60, which results in 30,705.88 meters per hour.

Now, since a kilometer is 1000 meters, this number must be divided by 1000 to determine the speed in kilometers per hour: 30,705.88 / 1000 = 30.7.

In this way, the speed of the ball was 30.7 km / h.