Posted by **Kevin** on Saturday, February 6, 2010 at 4:45pm.

A 90 kg halfback runs north and is tackled by a 120 kg opponent running south at 4 m/s. The collision is perfectly inelastic. Just after the tackle, both players move at a velocity of 2 m/s north. Calculate the velocity of the 90 kg player just before the tackle.

a.) 3 m/s south

b.) 4 m/s south

c.) 10 m/s north

d.) 12 m/s north

- Physics -
**Priscilla**, Saturday, February 6, 2010 at 5:24pm
Given

mA = 90 kg

MAf = 2 m/s

mB = 120 kg

MAi = 4 m/s

MAf = 2 m/s

Use the equation:::

(MA)(VAf) + (MB) (VBf) = (MA)(VAi) + (MB)(MBi)

If you have any questions, just reply back.

- Physics -
**Damon**, Saturday, February 6, 2010 at 5:25pm
north momentums:

before

90 v - 120 * 4

after

(90+120) * 2

set those equal and solve for v

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