PHYSICS CONNECTION
Density determines upthrust; force balance determines motion
Upthrust is the weight of displaced fluid. Compare it with the object’s weight and other forces to decide whether the object floats, sinks or accelerates.
Upthrust = ρfluid Vdisplaced g
Follow the reasoning
- Find the volume of fluid actually displaced.
- Calculate upthrust and weight separately.
- Use the resultant to explain the motion or equilibrium.
OFFICIAL OCR QUESTIONS
Try it in a past paper 2
Open the question, then use its mark scheme to check your work.
Question 2
Use repeated diameter readings, density and upthrust to analyse a floating cylinder.
Question 1(d)–(e)
Use tangents and terminal speed to analyse a steel ball falling through oil.
A curated collection checked against the question papers and mark schemes; not a complete past-paper catalogue. Links open official OCR PDFs in a new tab.
ORIGINAL PHYSICSUK QUESTIONS
Put the ideas to work
More practice is on its way
No PhysicsUK question linked yet. New eligible questions appear here as the bank grows.
Specification outcomes (5)
- 3.2.4(a) Define density; ρ = m / V.
- 3.2.4(c) Use p = hρg to calculate pressure in fluids; understand upthrust and Archimedes’ principle.
- 3.2.1(a) Apply Newton’s second law, F = ma.
- 3.2.1(c) Understand weight of an object, W = mg.
- 3.2.1(d) Define and identify tension, normal contact force, upthrust and friction.