List of top Biomechanics Questions on Kinematics of muscles and joints asked in GATE BM

Figure 1 depicts an arm holding a ball in static equilibrium. Figure 2 shows the free-body diagram of the lower arm where \(F\) is the force applied by the biceps muscle at an angle of \(\theta = 60\) degrees with respect to the lower arm, and \(R_1\) and \(R_2\) are the reaction forces acting at point O. The weights of the ball and the lower arm are \(W_1 = 50\) Newtons (N) and \(W_2 = 20\) N, respectively. The force exerted by the biceps muscle is \(F =\) N. (Round off to the nearest integer)

Assume the lower arm to be a rigid body.

In the free-body diagram, measured along the lower arm from the pivot O: the biceps force \(F\) acts at \(4\) cm from O; the forearm's weight \(W_2\) acts a further \(12\) cm beyond that (i.e. \(16\) cm from O); and the ball's weight \(W_1\) acts a further \(16\) cm beyond that (i.e. \(32\) cm from O).

The deltoid muscle connects the humerus to the shoulder blade and facilitates outstretching of the arm as shown in the figure. Assume the equivalent weight (W) of the arm to be 30 N and acts vertically down at a horizontal distance of 30 cm. Assume that the deltoid muscle is connected to the humerus at a distance of 15 cm and makes an average angle of $20^\circ$ with the horizontal. The magnitude of tension in the deltoid muscle is _________ N.

For blood flow through arteries, which one of the following relations approximates the pulse wave propagation speed \( C \) as a function of the inner diameter \( D \) of the artery, wall thickness \( t \), modulus of elasticity \( E \), and fluid density \( \rho \)?

Skeletal muscles are recruited to lift loads. If the force generated in the muscle due to contraction is not sufficient to lift the load, it is known as _________ contraction.