Please help with these questions !!<br /><BR>1. A rope is towing a 100 kg rock, from rest, with a force of 10 N that varies with time. At the end of 8.0 sec, the velocity of the rock is?<br /><BR>Answer is: zero<br /><BR><br /><BR>2. A 3 kg mass is positioned at (0,8) and a 1 kg mass is postioned at (12,0). What are the coordinates of a 4 kg mass which will result in the center of the mass of the system of three masses being located at the origin (0,0)?<br /><BR>The answer is (-3,-6)<br /><BR><br /><BR>3. A car traveling 20 m/s rounds an 80 m radius horizontal curve with the tires on the verge of slipping. How fast can this car round a second curve of radius 320 m? (assume the same coefficient of friction between the car's tires and each road surface).<br /><BR>The answer is: 40 m/s<br /><BR><br /><BR>Thanks !! <BR>