End `A` of the bar `AB` in figure rests on a frictionless horizontal surface and end `B` is hinged. A horizontal force `vecF` of magnitude `120 N` is exerted on end `A`. You can ignore the weight of the bar. What is the net force exerted by the bar on the hinge at `B`?

Options

A. `200N`
B. `140N`
C. `100N`
D. none of these

Answer

A

Explanation

The horizontal component of the force ederted on the bar by the hinge must balance the applied force `vecF`, nnd os has magnitude `120.0N` and is to the left. Taking torques bout point `A, (120.0N)(4.00m)+F_(v)(3.0m)` so the vertical componnet is `-160N, ` with the minus sign indicting a downward compnent, exerting torque in a directin opposite that of the horizontal component. the force exerted by the bar on the hinge is equal in magnitude and opposite in direction of the force exertd by the hinge on the bar.
Net force `sqrt("["(160)^(2))+(140)^(2)"]"=200N`