Question
The cg of the 50.0 N pole held by the pole vaulter is 2.00 m from the left hand, and the hands are
0.700 m apart. Calculate the force exerted by each hand.
0.700 m apart. Calculate the force exerted by each hand.
Answers
MathMate
This is a problem of levers which can be solved by taking moments.
Three forces are involved, L the left hand, R the right hand, and W the weight of the pole equal to 50N.
It is not clear but will be <i>assumed</i> that the cg of the pole is 2.00m to the <i>left</i> of the left hand, as follows.
---------------W---2.0----L--0.7--R----
Take moments about L, then forces W and R are both acting downwards so as not to create a couple.
2.0W=0.7R
Solve for R (knowing that W=50N)
Now take moments about R, i.e. put a fulcrum at R.
To counter the rotation created by the downwards force W, L must act upwards.
2.7W=0.7L
Solve for L.
Three forces are involved, L the left hand, R the right hand, and W the weight of the pole equal to 50N.
It is not clear but will be <i>assumed</i> that the cg of the pole is 2.00m to the <i>left</i> of the left hand, as follows.
---------------W---2.0----L--0.7--R----
Take moments about L, then forces W and R are both acting downwards so as not to create a couple.
2.0W=0.7R
Solve for R (knowing that W=50N)
Now take moments about R, i.e. put a fulcrum at R.
To counter the rotation created by the downwards force W, L must act upwards.
2.7W=0.7L
Solve for L.