- #1

Celestial92

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## Homework Statement

Two Cars

Yellow: Moving South

Green: Moving West

Green car stop in center of intersection and gets hit on from south bound Yellow Car

They collide, at intersection, find initial velocity, impact velocity and momentum (this confuses me)

Yellow Mass - 1356 kg

Green Mass - 829 kg

Skid Marks

North-South - 13.18m

East-West - 11.2m

Curved Skid - 3.442 (don't know how relevant)

Yellow front tire is 18.35m from southern end of north-south skids marks (again, not sure how relevant)

Kinetic Friction - 0.8

According to tutor, not able to use energy or time at all. Conservation of momentum should be enough.

I THINK the collision is inelastic and total momentum is conserved.

## Homework Equations

[itex]v^2 = u^2 + 2as[/itex]

[itex]m_1v_1 + m_2v_2 = m_1v_1 + m_2v_2[/itex]

## The Attempt at a Solution

I believe I was able to figure out the initial velocities, but don't know how to proceed or even if I am correct.

Friction Force = (-0.8) * (9.81) = -7.84 m/s^2

Yellow

[itex]u^2 = v^2 + 2as[/itex]

[itex]u^2 = 0 + 2 * -7.84 * 13.18[/itex]

[itex]u^2 = -206.66[/itex]

[itex]u = \sqrt{266.66}[/itex]

[itex]u = 14.37 m/s[/itex]

Same for Green car to get 13.25 m/s

Please help if you are able, the first set of answers (using time and energy) were not accepted as I didn't know you couldn't use them.

#### Attachments

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