Question

Consider a woman lifting a 60N. Find the tension in her back muscle and compression in her spine muscle when her back is horizontal. Approximate the situation as shown in (b) and assume this upper part of her body to weigh 250N with the centre of gravity as indicated. ​

Answer 1

Answer:

Explanation:

Here x := distance between the line of force of block and the force of 250 N.

'pivot point' is in the woman's waist s meters from force of 250 N.

M(back)  - 250 s - 60 ( s + x ) = 0

∴  M(back) = 250 s + 60 ( s + x)

Let the spring constant of muscles is k.

Distance from waist to the point of max tension in the back muscles is d.

Tension(T) and compression(c) will be

T = M(back) / d = 250 s + 60 ( s + x)/ d

c = T/k = 250 s + 60 ( s + x)/ kd