ANsume a person benis Torward to lift a load "with s buk as shown in Figure P12.48a. The spine pivota iuly at the fifth lumbar vertebra, with the princinal pporting force provided by the erector spinalis muscle in the back. To see the magnitude of the forces involved. consider the model shown in Figure P12.48b for a per- son bending forward to lift a 200-N object. The spine and upper body are represented as a uniform horizontal rod of weight 350 N. pivoted at the base of the spine. The erec tor spinalis muscle, attached at a point two-thirds of the way up the spine, maintains the position ofthe back.The Back muscle R, Pivot T 12.0 200 N 350 N Figure P12.48 angle between the spine and this musele is 0 == 12.0°. Find (a) the tension T'in the back muscle and (b) the compres- sjonal force in the spine. -
Simple harmonic motion
Simple harmonic motion is a type of periodic motion in which an object undergoes oscillatory motion. The restoring force exerted by the object exhibiting SHM is proportional to the displacement from the equilibrium position. The force is directed towards the mean position. We see many examples of SHM around us, common ones are the motion of a pendulum, spring and vibration of strings in musical instruments, and so on.
Simple Pendulum
A simple pendulum comprises a heavy mass (called bob) attached to one end of the weightless and flexible string.
Oscillation
In Physics, oscillation means a repetitive motion that happens in a variation with respect to time. There is usually a central value, where the object would be at rest. Additionally, there are two or more positions between which the repetitive motion takes place. In mathematics, oscillations can also be described as vibrations. The most common examples of oscillation that is seen in daily lives include the alternating current (AC) or the motion of a moving pendulum.
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