Pressure Between Solids Flashcards
What does the knife do when it cuts into the clay?
The knife applies a force that creates pressure on the clay, allowing it to cut through.
How can pressure be defined in the context of force?
Pressure is the pushing effect of a force.
If the clay is difficult to cut, what are two ways to increase the pressure exerted by the knife?
- Increase the force on the knife.
- Use a sharper knife, which reduces the surface area in contact with the clay.
Why does using a sharper knife increase the pressure on the clay?
A sharper knife has less surface area in contact with the clay, so as the area decreases, the pressure increases.
What is the equation that links pressure, force, and area?
Pressure = Force / Area
What are the units used for pressure, force, and area?
Pressure: newtons per meter squared (N/m²)
• Force: newtons (N) • Area: meters squared (m²)
If the area is measured in cm² instead of m², how would the units for pressure change?
The unit of pressure would be N/cm².
How can changing the area affect pressure?
Decreasing the area increases pressure, while increasing the area decreases pressure.
What happens to pressure when force increases while the area remains constant?
Pressure increases.
How does surface area relate to the effectiveness of cutting with a knife?
A smaller surface area results in higher pressure, making it easier to cut through materials.
These flashcards cover the key concepts and equations related to the pressure effect of a force, making it easier to study and understand.
What is the formula for calculating pressure?
Pressure = Force / Area
How is the pressure exerted by an elephant calculated in the example?
Given:
• Weight of the elephant: 50,000 N • Total area of all four feet: 0.4 m²
Calculation:
Pressure = 50,000 N / 0.4 m² = 125,000 N/m²
What unit is used for pressure in the elephant example, and why?
The unit of pressure is N/m² because the area is given in square meters.
In the bicycle example, what is the total weight of the bicycle and rider?
The total weight is 1,000 N.
How do you calculate the pressure each tyre of the bicycle exerts on the ground?
A: Given:
• Total weight: 1,000 N • Area of each tyre: 5 cm²
Steps:
1. Weight on each tyre = 1,000 N / 2 = 500 N 2. Pressure = 500 N / 5 cm² = 100 N/cm²
Why is the unit for pressure N/cm² in the bicycle example?
Because the area of the tyres is given in square centimeters.
What is the equation that links pressure, force, and area?
Pressure = Force / Area
How does the equation explain why a nail has a sharp point?
A sharp point decreases the area, which increases the pressure for the same force, making it easier to drive the nail into the wood.
Why are shoes for walking on snow wide and flat?
The wide and flat shape increases the area, which decreases the pressure, helping to prevent sinking into the snow.
What are the units of pressure when force is in newtons and area is in:
• m²? N/m²
• cm²? N/cm²
• mm²? N/mm²
A box weighs 60 N and has an area of 0.5 m² in contact with the ground. How do you calculate the pressure it exerts on the ground?
A: Calculation:
Pressure = Force / Area = 60 N / 0.5 m² = 120 N/m²
Q: A car weighing 8000 N is supported by 4 tyres. If the area of one tyre is 150 cm², what is the pressure exerted by one tyre on the ground?
Steps:
1. Weight on each tyre = 8000 N / 4 = 2000 N 2. Pressure = Force / Area = 2000 N / 150 cm² = 13.33 N/cm²
A thumb tack has an area of 0.5 mm² in contact with a wall, and a pressure of 40 N/mm² is needed to push it into the wall. How do you calculate the force needed?
Calculation:
Force = Pressure × Area = 40 N/mm² × 0.5 mm² = 20 N
