fisica1-youn-e-freedman-exercicios-resolvidos

5.126: In all cases, the tension in the string will be half of F.
a) F 2 = 62 N, which is insufficient to raise either block; a
1
= a2
= 0.
b) F 2 = 62 N. The larger block (of weight 196 N) will not move, so a = 0 1
, but the
smaller block, of weight 98 N, has a net upward force of 49 N applied to it, and so will
49 N
2
accelerate upwards with a = 4.9 m s .
2
=
10.0 kg
c) F 2 = 212 N, so the net upward force on block A is 16 N and that on block B is
114 N, so
114 N
2
a and a = 11.4 m s .
16 N
2
1
= = 0.8 m s
20.0 kg
2
=
10.0 kg
5.127: Before the horizontal string is cut, the ball is in equilibrium, and the vertical
component of the tension force must balance the weight, so T A
cos β = w,
or
T A
= w cos β. At point B, the ball is not in equilibrium; its speed is instantaneously 0, so
there is no radial acceleration, and the tension force must balance the radial component of
the weight, so T B
= w cos β,
and the ratio ( T T ) cos
2 β.
B A
=