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Let two objects of equal mass m collide. Object 1 has initial velocity v, directed to the right, and object 2 is initially stationary.

A. If the collision is perfectly elastic, what are the final velocities v1 and v2 of objects 1 and 2?

Give the velocity v1 of object 1 followed by the velocity v2 of object 2, separated by a comma. Express each velocity in terms of v.

Respuesta :

Answer:

(v, 0) or (0, v)

Explanation:

The law of conservation of linear momentum states total initial momentum equal total final momentum.

Total initial momentum = [tex]mv + m\times 0 = mv[/tex]

Total final momentum = [tex]mv_1 + mv_2 = m(v_1+v_2)[/tex]

Equating both,

[tex]mv = m(v_1+v_2)[/tex]

[tex]v = v_1+v_2[/tex]

For an elastic collision, kinetic energy is conserved i.e. total initial kinetic energy = total final kinetic energy

[tex]\frac{1}{2}mv^2 + \frac{1}{2}m\times0^2 = \frac{1}{2}mv_1^2 + \frac{1}{2}mv_2^2[/tex]

[tex]v^2 = v_1^2+v_2^2[/tex]

From the first equation, [tex]v_1 = v-v_2[/tex].

Substituting this in the second equation,

[tex]v^2 = (v-v_2)^2+v_2^2[/tex]

[tex]v^2 = v^2-2vv_2 +v_2^2+v_2^2[/tex]

[tex]0 = 2v_2^2-2vv_2[/tex]

[tex]v_2(v_2-v) = 0[/tex]

[tex]v_2 = 0[/tex] or [tex]v_2 = v[/tex]

From [tex]v_1 = v-v_2[/tex],

[tex]v_1 = v-v = 0[/tex]

OR

[tex]v_1 = v-0 = v[/tex]