A 7.30 kg sign hangs from two wires. The first wire is attached to the left end, and pulls 28.0 N directly left. What is the y-component of the force of the second wire?

Respuesta :

Answer:

Approximately [tex]71.6\; {\rm N}[/tex] (assuming that [tex]g = 9.81\; {\rm N \cdot kg^{-1}}[/tex].)

Explanation:

Refer to the diagram attached. Forces on this object are:

  • Tension on the left, from the wire on the left end.
  • Tension on the right, from the wire on the other end.
  • Weight, from the planet.

Assuming that [tex]g = 9.81\; {\rm N \cdot kg^{-1}}[/tex], the magnitude of the weight of the sign would be:

[tex]\begin{aligned}(\text{weight}) &= m\, g \\ &= (7.30\; {\rm kg})\, (9.81\; {\rm N\cdot kg^{-1}}) \\ &\approx 71.6\; {\rm N}\end{aligned}[/tex].

Note that weight points downwards (negative) and is entirely in the vertical direction. As a result, the [tex]y[/tex]-component of weight would be equal to [tex](-71.6)\; {\rm N}[/tex].

Hence, the [tex]y[/tex]-component of these forces would be:

  • [tex]0\; {\rm N}[/tex] for the wire on the left end, since this tension is entirely horizontal (entirely in the [tex]x[/tex]-direction,)
  • [tex](-71.6)\; {\rm N}[/tex] for the weight, which points downwards, and
  • Not yet found for the tension from the other wire.

Since forces on the object to be balanced, forces need to be balanced in each component. For forces in the [tex]y[/tex]-component to be balanced, forces in the vertical direction need to add up to [tex]0\; {\rm N}[/tex]:

[tex]0\; {\rm N} + (-71.6)\; {\rm N} + (\text{$y$-component of tension on the right}) = 0\; {\rm N}[/tex].

Hence, the [tex]y[/tex]-component of the tension from the wire on the right end would be [tex]71.6\; {\rm N}[/tex].

Ver imagen jacob193