479 Horizontal Motion: The horizontal component of velocity ... - Wuala

91962_05_R1_p0479-0512 6/5/09 3:53 PM Page 490
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*R1–16. The block has a mass of 50 kg and rests on the
surface of the cart having a mass of 75 kg. If the spring
which is attached to the cart and not the block is
compressed 0.2 m and the system is released from rest,
determine the speed of the block with respect to the cart
after the spring becomes undeformed. Neglect the mass of
the cart’s wheels and the spring in the calculation. Also
neglect friction. Take k = 300 N>m.
k
B
C
T 1 + V 1 = T 2 + V 2
[0 + 0] + 1 2 (300)(0.2)2 = 1 2 (50)v2 b + 1 2 (75) v2 e
12 = 50 v 2 b + 75 v 2 e
( : + ) ©mv 1 =©mv 2
0 + 0 = 50 v b - 75 v e
v b = 1.5 v e
v c = 0.253 m>s ;
v b = 0.379 m>s :
v b = v c + v b>c
( : + ) 0.379 = -0.253 + v b>c
v b>c = 0.632 m>s :
Ans.
490