A two-point system consists of two masses, m & 2m, separated by a distance d. If the mass m is replaced by a mass 3m and is kept at a distance d/2, what are the ratios of the gravitational potential energy of the two systems

The particle p starts from rest at point a at time t = 0 and changes its speed thereafter at a constant rate of 2.8g as it follows the horizontal path shown. determine the magnitude and direction of its total acceleration (a) just before point b, (b) just after point b, and (c) as it passes point c. state your directions relative to the x-axis shown (ccw positive) and choose the angle with the smallest magnitude.