Question

Part 1: How much pressure is applied to the ground by a 50 kg man who is standing on two square stilts that measure 0.04 m on each edge? Answer in units of Pa.
Part 2: What is this pressure in pounds per square inch? Answer in units of lb/in2.

Answer 1

To calculate the pressure applied to the ground by the man standing on the stilts, we can use the formula for pressure, which is given by:

\[
P = \frac{F}{A}
\]

### Part 1: Pressure in Pascals (Pa)

1. **Calculate the Force (F):**
The force exerted by the man is equal to his weight, which can be calculated using the formula \( F = mg \), where:
- \( m = 50 \, \text{kg} \) (mass of the man)
- \( g \approx 9.81 \, \text{m/s}^2 \) (acceleration due to gravity)

\[
F = 50 \, \text{kg} \times 9.81 \, \text{m/s}^2 = 490.5 \, \text{N}
\]

2. **Calculate the Area (A) of one stilt:**
The area of one square stilt can be calculated using the formula for the area of a square, \( A = s^2 \), where \( s \) is the length of one side.

Given that each edge of the stilt measures 0.04 m:
\[
A = (0.04 \, \text{m})^2 = 0.0016 \, \text{m}^2
\]

3. **Calculate the total area (A_total) for two stilts:**
\[
A_{\text{total}} = 2 \times A = 2 \times 0.0016 \, \text{m}^2 = 0.0032 \, \text{m}^2
\]

4. **Calculate the pressure (P):**
\[
P = \frac{F}{A_{\text{total}}} = \frac{490.5 \, \text{N}}{0.0032 \, \text{m}^2} \approx 153281.25 \, \text{Pa}
\]

### Part 2: Pressure in Pounds per Square Inch (lb/in²)

1. **Convert the pressure from Pascals to lb/in²:**
To convert from Pascals to lb/in², we use the following conversion factors:
- 1 Pascal (Pa) = 0.0001450377 lb/in² (psi)

So, we convert the pressure:
\[
P \approx 153281.25 \, \text{Pa} \times 0.0001450377 \, \text{lb/in}^2/\text{Pa} \approx 22.195 \, \text{lb/in}^2
\]

### Final Answers:
Part 1: The pressure applied to the ground is approximately **153281.25 Pa**.
Part 2: The pressure is approximately **22.195 lb/in²**.