4. Same arrangement as in problem 3. If the sphere is released at a height h = 3R, what is the force exerted by the track at the top of the loop? (A) 2mg (B) mg (C) 0.5mg (D) mg(R + 3r)/(R − r) (E) mg(R + r)/(R − 4)

3. A solid sphere of mass m and radius r moves along a track with a circular loop of radius R1 as shown in following picture. It is released at height h. Assuming that the track has no friction, the ball thereforeslides down without rotation. Do not ignore the finite size of the sphere, what is the minimal value of h such that the sphere remains on the track at all times? (A) 2.5R − 1.5r (B) 2R − r (C) 2.5R (D) 2R + r (E) 2R − 1.5r

4. Same arrangement as in problem 3. If the sphere is released at a height h = 3R, what is the force exerted by the track at the top of the loop?
(A) 2mg
(B) mg
(C) 0.5mg
(D) mg(R + 3r)/(R − r)
(E) mg(R + r)/(R − 4)

相關試題

相關試卷