Block A in the figure (Figure 1) weighs 1.30N and block B weighs 3.59N . The coe
ID: 1294281 • Letter: B
Question
Block A in the figure (Figure 1) weighs 1.30N and block Bweighs 3.59N . The coefficient of kinetic friction between all surfaces is 0.291.
1-Find the magnitude of the horizontal force F? necessary to drag block B to the left at constant speed if A rests on B and moves with it (figure (a)).
2-Find the magnitude of the horizontal force F? necessary to drag block B to the left at constant speed if A is held at rest (figure (b)).
Block A in the figure (Figure 1) weighs 1.30N and block Bweighs 3.59N . The coefficient of kinetic friction between all surfaces is 0.291. 1-Find the magnitude of the horizontal force F? necessary to drag block B to the left at constant speed if A rests on B and moves with it (figure (a)). 2-Find the magnitude of the horizontal force F? necessary to drag block B to the left at constant speed if A is held at rest (figure (b)).Explanation / Answer
(1)
Since it is moving at constant speed, the net force is zero. That is,
Fnet = 0 N
Apply the Newton's second law and solve for horizontal force.
Fnet = Fapp - Ff
0 = Fapp - Ff
Fapp = Ff
Ff = ?Fn
Ff = (0.291) (3.59 N + 1.30 N)
= 1.423 N
2.
Apply the Newton's second law to the blocks and solve for horizontal force.
Fnet = Fapp -Ff(A+B on the floor) - Ff (A on B)
0 = Fapp - Ff(A+B on the floor) - Ff (A on B)
Hence, the horizontal force is,
Fapp = (0.291) (3.59 N+1.30 N) + (0.291)(1.30 N)
= 1.80 N