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A 1500 kg car travels at 90 km/h east and collides with a 1000 kg car traveling at 60 km/h north. The two cars stick together after the collision. The road surface conditions were wet such that us= 0.5 and uk = 0.4. What is the speed of the cars, in m/s, immediately after the collision? What is the direction of the velocity of the cars immediately after collision? How far did the two vehicles skid, in meters, after the collision?

Answer :

Answer:

direction = [tex]\frac{4}{\sqrt{97} }i+\frac{9}{\sqrt{97} }j[/tex]

velocity = [tex]\frac{30\times \sqrt{97} }{5}[/tex]

distance skid = 145.2 meters

Explanation:

Let the mass of the car 1 m1 = 1500 kg, m2 = 1000 kg, v1 = 90 km/h and v2 = 60 km/h.

v1 = 90 i and v2 = 60 j.

applying conservation of linear momentum in i and j direction since there is no external force involved.

along i direction:

[tex]m1\times v1 = (m1+m2)\times v\times \cos \Phi[/tex]           1

along j direction:

[tex]m2\times v2 = (m1+m2)\times v\times \sin \Phi[/tex]          2

where v is the new velocity of combined car and Ф is the angle made with x axis.

equation 2÷1

[tex]\tan \Phi =\frac{m2\times v2}{m1\times v1}[/tex]

therefore \tan \Phi = \frac{4}{9}

[tex]\sin \Phi =\frac{4}{\sqrt{97} }[/tex]

[tex]\cos \Phi =\frac{9}{\sqrt{97} }[/tex]

therefore the direction is[tex]\frac{4}{\sqrt{97} }i+\frac{9}{\sqrt{97} }j[/tex]

and velocity will be

[tex]\frac{30\times \sqrt{97} }{5}[/tex]

the car will skid until the total energy of the car is dissipiated by friction

therefore [tex]u\times (m1+m2)\times g\times x=\frac{1}{2}\times (m1+m2)\times v^{2}[/tex]

substituting the values we get x = 145.2 meters

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