A 110 kg football player running with a velocity of 5.0 m/s hits another stationary football player who has a mass of 90 kg. Upon impact, the first player immediately stops, thus propelling
the second player backwards. What is the final velocity of the second player?

The final velocity of the second player is 6.1 m/s.

Explanation:

The final velocity of the second player can be calculated by conservation of linear momentum (p):

 (1)

Where:

: is the mass of the first football player = 110 kg

: is the mass of the second football player = 90 kg

: is the initial velocity of the first football player = 5.0 m/s

: is the initial velocity of the second football player = 0 (he is at rest)

: is the final velocity of the first football player = 0 (he stops after the impact)

: is the final velocity of the second football player =?

By solving equation (1) for we have:

Therefore, the final velocity of the second player is 6.1 m/s.

I hope it helps you!

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form