1. 52. The cube has side length l and volume V = l3 . We use p = B∆V /V for the pressure p. We note that
∆V ∆l3 (l + ∆l)3 − l3 3l2 ∆l ∆l
= 3 = 3
≈ 3
=3 .
V l l l l
Thus, the pressure required is
2
3B∆l 3 1.4 × 1011 N/m (85.5 cm − 85.0 cm)
2
p= = = 2.4 × 109 N/m .
l 85.5 cm