Question

Work Done by Normal Force Consider an object sliding along the surface shown below. Choose and show a direction of motion for the object and show the direction of the normal force. Use this figure to do the scalar product given below. oM bns av W, n-s Is the work done by the normal force exerted between two colliding objects also zero? Explain. Work Done by Weight Unlike the normal and kinetic friction forces, the direction of an object's motion is independent of the direction of its weight. In other words, an object experiences a downward force of gravity regardless of which direction it moves. Since the direction of this force is fixed, it is easiest to consider the work done by weight by writing these vectors in component form. Consider the projectile of mass m shown below. The directions of its weight and motion vectors are shown below. The object's general displacement and weight vectors are given below in component form. Do this scalar product to obtain an equation for the work done by weight. s=,i+s,j W -mgj mg Is the work done by weight positive, negative, or zero for an object moving a) up, b) horizontally, and c) down?

Answer 1

sol: work done by Normal force + let object slides down and cover distance 's' along songs samp: ringsing To ng mgcoso Force ' n Work done by normal force, Whaños Band ( anangle between N S = 90° ) a mgws OxSxW890' N = nguoso [ Wn= g { casgo=0} Work done by normal force = 0 & work done ky Normal force entented between two colliding object is always zero. mes uncinplo neuetun's 7 Taw Soll's * during collieren, afizə Fed both borees are equal no so, work, Fids = -fods + Fds=0 fasds is same in Co I work done =0) always. Sasnal Syj ; Wg was ; w=-mg ĵ so, @ Work done in moving up @ W = Woš= -mgs =-ve 6 Horizontally, anio, Tw=o) 6 down, Wang .(-5) = mgs e possitive . (downward =-ue) o