If the horizontal force F = 20 lb is applied to block A, determine the accleration of block B. Neglect the firction if any.

1) 7.0 ft/s2
2) 7.3 ft/s2
3) 8.3 ft/s2
4) 9.5 ft/s2

From the free body diagram shown
For block A:
S
Fx = max and 20-NB sin30o = (8/32.2)aA   ---------(1)

For block B:
S Fy = may and NB cos30o - 10 = (10/32.2)aB ------(2)
and sB = sAtan30o and aB = aAtan30o -----------------(3)
where sA and sB are distances travelled by blocks A and B in x and y directions respectively.

Solving equations (1)-(3) we have
aA = 12.63 ft/s2 and  NB = 16.077 lb 
aB = 7.29 ft/s2

So, the accleration of block B, aB = 7.29 ft/s2