A30 kg girl sits on a seesaw 4.0 m from the fulcrum. what distance from the fulcrum should a 40kg boy sit in order to balance the seesaw

The answer is 3m

Explanation:

This question has to do with balancing of moment

The moment of force about the fulcrum

Given the mass of the girl =30kg

To force Fg=30*10=300N

Distance of girl from fulcrum l= 4m

Mass of boy 40kg

TO force Fb=40*10=400N

Distance of the boy from fulcrum =?

We know that moment of force about a point M=force*distance

I.e M=f*l

For the boy to cause a balance

His moment must be equal to that of the girls

Therefore

Fg*l=Fb*l

300*4=400*l

1200=400l

L=1200/400

L=3m

Hence the boy must seat 3m away from the fulcrum to balance the seesaw

What is a moment?

A moment is a turning force about a point, The moment is equal to the magnitude of the force multiplied by the perpendicular distance between its line of action and the axis of rotation