A runner ran the marathon approximately 420 km in 2 hours an

A runner ran the marathon (approximately 42.0 km) in 2 hours and 57 min. What is the average speed of the runner in m/s? 14.2 times 10^3 m/s 124 m/s 3.95 m/s 14.2 m/s 55 mi/h is how many m/s? (1 mi = 1609 m.) 25 m/s 49 m/s 90 m/s 120 m/s If you are driving 72 km/ft along a straight road and you look to the side for 4.0 s how far do you travel during this inattentive period? 18m 20 m 40 m 80 m A polar bear starts at the North Pole. It travels 1.0 km south, then 1.0 km east, then 1.0 km north, then 1.0 km west to return to its starting point. This trip takes 45 min. What was the bear\'s average speed? 0 km/h 4.5 km/h 0.09 km/h 5 3 km/h

Solution

11.

Distance =42000 m

Time = 2 hours 57 min=2*3600+57*60=10620 s

Hence average speed =42000/10620~3.95 m/s

12.

1 mi =1609 m

1 h =3600 s

So,

55 mi/h=55*1609/3600 ~24.58 =25 m/s

13)

Speed=72*1000/3600=20 m/s

So distance travelled in 4 s =80 m

14)

Total distance travelled =4 km

Time for travelling =45 min =45/60=3/4 hours=0.75 h

So average speed ,v=4/0.75~5.3 km/h