Question

I do not understand why the radius relative to the ball is .7 cm. I do not understand how to visualize this question.

Answer 1

Answer:

Step-by-step explanation:

The mass of the steel ball, m₁ = 3.0 kg

The mass of the arm, m₂ = 4.0 kg

The length of the arm, r = 7 cm

r = 7/100

r = 0.7m

The angle between the shoulder and the arm = θ

The magnitude of the torque is given by the formula:

`\tau=Fr\sin \theta`

The force, F, is the combined weight of the steel ball and the arm

F = (m₁ + m₂)g

F = (3.0 + 4.0)(9.8)

F = 7(9.8)

F = 68.6N

a) The magnitude of the gravitational force about the athlete's shoulder if he holds his arm straight parallel to the floor

θ = 180°

`\begin{gathered} \tau\text{ = 68.6(0.7)}\sin 180 \\ \tau=48.02(0) \\ \tau\text{ = 0}Nm \end{gathered}`

b) 45° below horizontal

θ = 45°