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A box rests on a horizontal, frictionless surface. a girl pushes on the box with a force of 17 n to the right and a boy pushes on the box with a force of 13 n to the left. the box moves 3.5 m to the right. find the work done by (a) the girl, (b) the boy, and (c) the net force.

Respuesta :

Refer to the diagram shown below.

The net force acting on the box is 17 - 13 = 4 N to the right.
The box moves on a friction surface by 3.5 m to the right.

By definition,
Work = Force x Distance.

(a) The work done by the girl is
     W₁ = (17 N)*(3.5 m) = 59.5 J

(b) The work done by the boy is
     W₂ = (13 N)*(-3.5 m) = - 45.5 J

(c) The work done by the net force  is
    W₃ = (4 N)*(3.5 m) = 14 J

Note that W₃ = W₁ + W₂

Answers:
(a) 59.5 J
(b) - 45.5 J
(c) 14 J

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