The world's record in the 100 m dash is 9.69 seconds and in the 100 yard dash is 9.21 seconds.
a) find the speed in mi/h of the runner who set the record of 9.69 seconds.
b) find the speed in mi/h of the runner who set the record of 9.21 seconds.

A) The speed of the runner is 23.085 mile/hr.

B) The speed of the runner is 22.209 mile/hr.

Explanation:

A) Distance covered in 9.69 seconds = 100 m

1 mile = 1609.34 m

1 hour = 3600 seconds

9.69 s =

Speed of the runner =

The speed of the runner is 23.085 mile/hr.

B) Distance covered in 9.21 seconds = 100 yards

1 mile = 1760 yards

1 hour = 3600 seconds

9.21 s =

Speed of the runner =

The speed of the runner is 22.209 mile/hr.

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied