Question

Explain why we cannot bend our arm if a light wooden plank is tied to it

Answer 1

because plank will exert equal and opposite force on hand

Answer 2

HEY MATE YOUR ANSWER IS: I THINK WE CANNOT BEND OUR ARM IF A LIGHT WOODEN PLANK IS TIED TO OUR MUSCLE PARTS FROM BEING BENDING . IT KEEPS OUR ARM STRAIGHT. I HOPE THAT MY ANSWER HELPFUL