In physics language, you would ask how much is the normal force on the feet compared to the hands, and how these normal forces compare with the person's weight. Also, you could ask how much friction is on the feet compared with the hands. Downward Dog Remember Newton's 3\" Law; the normal forces exerted by the person on the floor is equal and opposite to the normal forces the floor exerts back on the person. is the System Intuitive Guess: Which exerts the most normal force on the floor? Bold your choice - feet - hands - the same Which exerts the most friction force on the floor? Bold your choice - feet - hands - the same Visualize Force Equilibrium: Balanced forces EFV = o EFX = 0 EFup = EFdown 2|:backward : ZFforward Sum of forces up balances Sum of forces forward balances sum of forces down sum of force backwards Downward Red: normal Blue : Weight iii it? Put tail of vector where force occurs Model weight at the center of mass, and normal and friction at middle of the contact surface Downward Dog EF. = 0 EF = 0 W nfeet + 0 + + = 0 nhands ffeet Drag vectors and labels to place in hands equations and resize Going from vector to algebraic representation Sign direction convention followed: Up positive, down negative Forward positive, backwards negative W + + nfeet + + 0 0 nhands + + ffeet fhands Drag labels and signs to make equations Sign indicates vector directionnfeet W Rearrange algebraic symbols and signs to solve for hands in terms of parameter(s) of known value: feet + + nback + Rearrange algebraic symbols and signs to solve for fback in terms of parameter(s) of known value: W feet ffeet handsIn physics language, you would ask how much is the normal force on the front foot compared to the back foot, and how these normal forces compare with the person's weight. Also, you could ask how much friction is on the front foot compared with the back foot. Remember Newton's 3'd Law; the normal forces exerted by the person on the floor is equal and opposite to the normal forces the floor exerts back on the person. Intuitive Guess: Which foot exerts the most normal force on the floor? Bold your choice - Front foot - Back foot - The same Which foot exerts the most friction force on the floor? Bold your choice - Front foot - Back foot - The same Visualize Force Equilibrium: Balanced forces . 2F = 0 Sun Salutatlon Y 2g=0 2:FUF' = ZFdown Z1Fbackward = 2|:forward Sum 01c forces UP balances sum Sum of forces forward balances sum of forces down of force backwards Red: normal Blue : Weight Green: friction Put tail of vector where force occurs Model weight at the center of mass, and normal and friction at middle of the contact surface Relative size of the vectors matters Sun salutation EF., = 0 EF. = 0 W nback + 0 + + 0 nfront ffront Drag vectors and labels to place in fback equations and resize Going from vector to algebraic representation Sign direction convention followed: Up positive, down negative Forward positive, backwards negative W + + nback + E 0 0 nfront + fback ffront Drag labels and signs to make equations Sign indicates vector directionRearrange algebraic symbols and signs to solve for back in terms of parameter(s) of known value: ffront nfront W + + nback + + Rearrange algebraic symbols and signs to solve for fback in terms of parameter(s) of known value: W front front back =Book being held in grasp Red: normal Blue : Weight Green: friction Book is the System Show only forces acting on the system Book being grasped EF., = 0 EF = 0 W nfingers + = 0 + + 0 nthumb ffingers Drag vectors and labels to place in fthumb equations and resize Going from vector to algebraic representation Sign direction convention followed: Up positive, down negative Forward positive, backwards negative W + + nfeet + 0 0 nhands + + ffeet fhands Drag labels and signs to make equations Sign indicates vector direction+ H O n f Sign direction convention followed: Going from vector to algebraic representation ' UP M: down W - Forward gositive, backwards negative 5 II 0 II o + _ Drag signs to make equations Si n indicates vector direction + + g