In an isometric exercise a person places a hand on a scale and pushes vertically downward, keeping the forearm horizontal. This is possible because the triceps muscle applies an upward force Marrowbold perpendicular to the arm, as the drawing indicates. The forearm weighs 20.0 N and has a center of gravity as indicated. The scale registers 122 N. Determine the magnitude of Marrowbold.

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530N

To determine the magnitude of the upward force Marrowbold applied by the triceps muscle, we need to analyze the forces acting on the forearm.

From the problem statement, we have:
- Weight of the forearm (vertical force due to gravity) = 20.0 N, acting downward
- Reading on the scale = 122 N, acting upward
- Marrowbold (upward force applied by the triceps muscle) = ?

To solve for Marrowbold, we need to consider equilibrium conditions. In equilibrium, the sum of all forces in both the vertical and horizontal directions is zero.

1. Vertical Forces:
Summing up the vertical forces, we have:
- Marrowbold (upward force applied by the triceps muscle)
- Weight of the forearm (20.0 N)
- Reading on the scale (122 N)

Since the forearm is in equilibrium, the sum of these forces should be zero. Therefore:
Marrowbold + Weight - Reading = 0

Rearranging the equation:
Marrowbold = Reading - Weight

Substituting the given values:
Marrowbold = 122 N - 20.0 N
Marrowbold = 102 N

So, the magnitude of the upward force Marrowbold applied by the triceps muscle is 102 N.