Question

3. A man holds a 100 N load stationary in his hand. The combined weight of the forearm and hand is 20 N. The forearm is held horizontal, as shown bcon lorem ON WO What is the vertical force F needed in the biceps? (a) 750 N (b) 800 N (c) 850 N con (d) 900 N​

Answer 1

Answer:

800 N maybe the correct answer.

Answer 2

Given:

Weight of load= 100N

Weight of the forearm and hand = 20 N

Distance between biceps and bone= 4cm

Distance between COM of the forearm and bone = 10cm

Distance between load and bone= 32cm

To Find:

Force F needed in the biceps

Solution:

Since the hand is in rotational equilibrium

⇒ The net torque on it is zero

Torque (T)= r X F

(r = distance from hinge and F = force)

Net Torque acting upwards= 4F Ncm

Net Torque acting downwards= (200+3200)Ncm

Equating the two,

4F = 3400

F= 850N

(No need of converting cm to m since it gets canceled while equating)

Hence, the vertical force F needed in the biceps is 850N.