A normal thrust (force) of 800 N acts uniformly on a flat surface of area 16 m^2. What is the resulting pressure on the surface, expressed in pascals (Pa)?

Introduction / Context:

Pressure is a fundamental quantity in mechanics and fluid statics, defined as force acting per unit area. Many introductory physics problems involve calculating pressure when you know the force (or thrust) and the contact area. This question gives you a thrust and an area and asks you to compute the pressure in SI units, testing both your understanding of the formula and your ability to handle simple numerical calculations.

Given Data / Assumptions:

• Thrust or normal force, F = 800 N.
• Area of contact, A = 16 m^2.
• Pressure P is defined as force per unit area, P = F / A.
• We are asked to express the answer in pascals (Pa), where 1 Pa = 1 N m^-2.

Concept / Approach:

The formula for pressure when a force acts normally on a surface is P = F / A. In SI units, if F is in newtons and A in square metres, the resulting pressure is in pascals. The question is a straightforward application of this formula: substitute F = 800 N and A = 16 m^2 into P = F / A and simplify. Careful division ensures you get the correct numerical value and avoid arithmetic mistakes.

Step-by-Step Solution:

Verification / Alternative check:

You can verify the arithmetic by noting that 16 multiplied by 50 equals 800 (16 * 5 = 80, then add one zero). This confirms that the division 800 / 16 gives 50 exactly. Units are also consistent: newtons divided by square metres give pascals. If either F or A had different units, you would need to convert them first, but here both are already in SI base units.

Why Other Options Are Wrong:

Option A (128 Pa): This would correspond to 800 / 6.25, not to the given area of 16 m^2. It indicates an incorrect division.

Option B (100 Pa): This would be correct only if the area were 8 m^2, since 800 / 8 = 100. It does not match the given data.

Option C (64 Pa): This would correspond to dividing 800 by 12.5, again inconsistent with the stated area.

Option E (800 Pa): This would imply that the area is 1 m^2, so that pressure equals force, which is not the case here.

Common Pitfalls:

There are two common errors in such questions. First, some students invert the formula and incorrectly calculate A / F, which would give the inverse of pressure, not pressure itself. Second, mistakes in simple division, especially when dealing with larger numbers, can lead to wrong answers even when the concept is understood. Always write the formula first, substitute carefully and check the arithmetic and units before choosing the final answer.

Final Answer:

The pressure on the surface is 50 Pa.