To increase stability, which changes are suggested?

• A. Increase surface area and make the object shorter
• B. Decrease surface area and make the object taller
• C. Increase mass without changing shape
• D. Move center of mass higher

Answer: (A)

Stability depends on where the weight acts relative to the base: a heavier weight is harder to tip only if the weight’s vertical line stays inside the base, and a wider base plus a lower center of gravity make tipping harder. Increasing the base area enlarges the footprint, so the vertical line through the weight can stay inside the base during tilting. Making the object shorter lowers the center of gravity, which reduces the tipping moment and makes it harder to topple. Together, these changes make the object more stable.

If you reduce the base or raise the center of gravity, tipping becomes easier. Merely increasing mass without changing shape doesn’t move the center of gravity, so it doesn’t improve stability, and moving the center of mass higher actually reduces stability.