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A block having mass m travels along a horizontal frictionless surface with speed vx. What impulse must be delivered to the mass to reverse its direction and continue to travel with a speed of vx?
A) -mvxB) -2mvxC) 0D) 2mvxE) mvxF) none of the aboveG) cannot be determined

Respuesta :

Answer:B

Explanation:

Given

mass of block is [tex]m[/tex]

Initial speed [tex]u=v_x[/tex]

final speed is reverse of initial with same magnitude [tex]v=-v_x[/tex]

Initial momentum [tex]P_i=mv_x[/tex]

Final momentum [tex]P_f=-mv_x[/tex]

change in momentum [tex]\Delta P=P_f-P_i[/tex]

Impulse [tex]J=\Delta P[/tex]

[tex]J=-mv_x-mv_x[/tex]

[tex]J=-2mv_x[/tex]

                     

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