$2, A force of 486 lb is necessary to keep a weight of exactly 800 lb from sliding down an inclined plane. What is the angle of inclination of the plane? Assume that friction is ignored.50. What is the minimum force necessary to keep a 250-1b barrel from sliding down an inclined plane (see Fig- ure 5.67) making an angle of 12 with the horizontal? What is the force against the plane? Assume that friction is ignored. 250-pound barrel inclined plane B a 250 lbs