The gravitational potential in a region is given by V=20Nkg−1 (x + Y). (a) show that the equation is dimensionally correct. (b) Find the gravitational field at the point (x,y), Leave your answer in terms of the unit vectors →i,→j,→K. N kg−1 (c) Calculate the magnitude of the gravitational force on a particle of mass 500 g placed at the origin.
(a)V=(20Nkg)(x+y)GMR=MLT−2M;LorM−1l3T−2M1L=ML2T−2MorM0L2T−2=M0L2T−2∴LHS=RHS(b)→E(x,y)=−20(NKG)^i−(20Nkg)^j(c)→F=→Em=0.5kg[−(20Nkg)−(20Nkg)^j]=−(10N)^i−(10N)^j∴|→F|=√(100)+(100)=10√2N