Explanation

To find the minimum external force needed to crack the windows, we can use the formula:

Force (F) = Pressure (P) × Area (A)

Given:

P = 660 kPa = 660,000 Pa (converting kPa to Pa)

Diameter (d) = 0.30 m

Radius (r) = d/2 = 0.15 m

Area (A) = πr² = π(0.15)² ≈ 0.0707 m²

Now, calculate the force:

F = P × A ≈ 660,000 Pa × 0.0707 m² ≈ 46,662 N ≈ 47,000 N