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1. There is a famous intersection in Kuala Lumpur, Malaysia, where thousands of vehicles pass each hour. A 750 kg Tesla Model S traveling south crashes into a 1250 kg Ford F-150 traveling east. What are the initial speeds of each vehicle before collision if they stick together after crashing into each other and move at an angle of 320 and a common velocity of 18 m/s.

Respuesta :

Solution :

Let the positive [tex]x-axis[/tex] is along the East and the positive [tex]y[/tex] direction is along the north.

Given :

Mass of the Tesla car, [tex]m_1[/tex] = [tex]750 \ kg[/tex]

Mass of the Ford car, [tex]m_2 = 1250 \ kg[/tex]

Now let the initial velocity of Tesla car in the south direction be = [tex]-v_1j[/tex]

The initial momentum of Tesla car, [tex]p_1 = -750 \ v_1[/tex]

Let the initial velocity of Ford car in the east direction be = [tex]v_2 \ i[/tex]

So the initial momentum of the Ford car is [tex]p_2=1250\ v_2 \ i[/tex]

Therefore, the initial velocity of both the cars is [tex]p_i = p_1+p_2[/tex]

                                                                  [tex]=1250 \ v_2 \ i - 750\ v_1 \ j[/tex]

Now the final velocity of both the cars is [tex]v = 18 \ m/s[/tex]

So the vector form is :

[tex]v = 18\cos 32\ i-18 \sin 32 \ j[/tex]

  [tex]= 15.26 \ i - 9.54 \ j[/tex]

Therefore the momentum after the accident is

[tex]p_f=(m_1+m_2) \times v[/tex]

    [tex]=(750+1250) \times (15.26 \ i - 9.54 \ j)[/tex]

    [tex]= 30520\ i -19080\ j[/tex]

According to the law of conservation of momentum, we know

[tex]p_i = p_f[/tex]

[tex]1250 \ v_2 \ i - 750\ v_1 \ j[/tex]  [tex]= 30520\ i -19080\ j[/tex]

[tex]1250 \ v_2 = 30520[/tex]

[tex]v_2=24.4 \ m/s[/tex]

From, [tex]750\ v_1 = 19080[/tex]

We get, [tex]v_1=25.4 \ m/s[/tex]

Therefore the speed of Tesla car before collision = 25.4 m/s

The speed of ford car before collision = 24.4 m/s

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