Pressure and Fluids

What this exam is like

The Pressure and Fluids exam has 34 multiple-choice questions across these levels: Primary (13), Secondary (34). Each attempt draws 10 at random from the level you choose. You get two tries per question, and each answer is explained afterwards. At the end you see your grade.

Sample questions

1. 1. Why does a sharp knife cut better than a blunt one, with the same force?

   • Because it concentrates the force on a much smaller area
   • Because it heats up more
   • Because it weighs less
   • Because sharp metal is harder
   Show the answer

   ✅ Because it concentrates the force on a much smaller area

   Pressure is force divided by area. Sharpening adds no force: it shrinks the area the force spreads over, so with the same force the pressure shoots up.

2. 2. In communicating vessels of different shapes, what level does the liquid settle at?

   • At the same height in all of them
   • Higher in the narrowest one
   • Higher in the widest one
   • It depends on the filling order
   Show the answer

   ✅ At the same height in all of them

   It follows directly from pressure depending only on height: if one side were higher there would be more pressure below on that side and the liquid would move until it evened out.

3. 3. A 600 N person stands on one foot of area 0.02 m². What pressure do they exert on the floor?

   • 12 Pa
   • 3,000 Pa
   • 30,000 Pa
   • 600 Pa
   Show the answer

   ✅ 30,000 Pa

   P = 600 ÷ 0.02 = 30,000 Pa. On both feet it would be half, 15,000 Pa: the same person exerts twice the pressure on one leg without gaining any weight.