Question

A weight lifter is trying to do a bicep curl with a weight of 300 N. At the "sticking point", the moment arm of this weight is 30 cm about the elbow axis of rotation. The maximum force that the elbow flexor muscles can create for this situation is 4000 N and the moment arm of the elbow flexors is 2 cm. Can the lifter get past this sticking point?

Answer 1

The weight lifter would not get past this sticking point.

Step-by-step explanation:

Generally torque applied on the weight is mathematically represented as

T = F z

To obtain Elbow torque we substitute 4000 N for F (the force ) and 2cm
`= (2)/(100) = 0.02m` for z the perpendicular distance

So Elbow Torque is
`T_e= 4000 * 0.02`

`= 80Nm`

To obtain the torque required we substitute 300 N for F and 30cm
`=(30)/(100) = 0.3 m`

So the Required Torque is
`T_R = 300 *0.3`

`=90Nm`

Now since
`T_e < T_R` it mean that the weight lifter would not get past this sticking point