The most energy-efficient way to send a spacecraft to the moon is to boost its speed while it is in circular orbit about the earth such that its new orbit is an ellipse. the boost point is the perigee of the ellipse, and the point of arrival at the moon is the apogee. calculate the percentage increase in speed required to achieve such an orbit. assume that the spacecraft is initially in a low-flying circular orbit about earth. the distance between earth and the moon is approximately 60 re, where re is the radius of earth

16. a brave but inadequate rugby player is being pushed backward by an opposing player who is exerting a force of 800 n on him. the mass of the losing player plus equipment is 90.0 kg, and he is accelerating at 1.20m/s2 size 12{1 "." "20"" m/s" rsup { size 8{2} } } {} backward. (a) what is the force of friction between the losing player’s feet and the grass? (b) what force does the winning player exert on the ground to move forward if his mass plus equipment is 110 kg? (c) draw a sketch of the situation showing the system of interest used to solve each part. for this situation, draw a free-body diagram and write the net force equation.