Two objects, a and b, are held one meter above the horiz'ontal ground. the mass of b is twice as great as the mass of a. if pe is the gravitational potential energy of a relative to the ground, then the gravitational potential energy of b relative to the ground 15? a) pe 13) 2pe c) 2p_e d) 4pe

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.

cell differentiation  is how generic embryonic  cells  become specialized  cells. this occurs  through a process called gene expression. gene expression is the specific combination of genes that are turned on or off (expressed or repressed), and this is what dictates how a  cell  functions.

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