Pressure

Pressure is dependent on ______________.

• force only

• force and surface area

• contact area only

• force and contact area

Which one is the correct formula relating force, pressure and area?

• F = P / A

• A = F x P

• P = F / A

• P = A /F

Which of the following is NOT a unit for pressure?

• Pa

• N/cm²

• Nm²

• N/m²

A ballet dancer en pointe (on tip toes) has a __________ contact area. Hence, pressure exerted on the floor is _________.

• big, big

• big, small

• small, big

• small, small

Wearing skis on snow spreads out the skier's weight, this

• increases pressure by increasing contact area

• increases pressure by decreasing contact area

• decreases pressure by increasing contact area

• decreases pressure by decreasing contact area

A sharp knife has

• a large contact area and a large pressure

• a small contact area and a large pressure

• a small contact area and a small pressure

• a large contact area and a small pressure

A piece of glass can withstand a pressure of 2.1 N/cm², what is the minimum force needed to break the glass with a special hammer of surface 3cm by 4cm?

• 9.3 N

• 16.8 N

• 8.4 N

• 25.2 N

Ice cracks if the pressure on it is more than 3000 N/m². A man of weight 900 N wants to safely walk over the ice. What should be the area of each of his snowboots?

• 0.15 m²

• 0.30 m²

• 1.67 m²

• 3.33 m²

Sam of weight 450 N sits on a chair with 4 legs. Each leg has a contact area of 3 cm by 6 cm with the ground. What is the pressure exerted on the ground?

• 6.25 Pa

• 25 Pa

• 6.25 N/cm²

• 25 N/cm²

Which would be the least likely to sink into soft ground?

• A loaded lorry with 4 wheels.

• An empty lorry with 4 wheels.

• A loaded lorry with 6 wheels.

• An empty lorry with 6 wheels.