H1 Physics 8867 · objective lesson
Uniform circular-motion kinematics and force
Use radians and v = rω; the inward resultant of real forces produces a = v²/r = rω².
Repair the common break
Common misconception: Centripetal force is an extra force added to real forces.
Correct model: Use radians and v = rω; the inward resultant of real forces produces a = v²/r = rω².
Worked transfer
A 0.80 kg mass moving at 5.0 m s⁻¹ in a 2.0 m circle needs inward resultant mv²/r = 10 N. ‘Centripetal force’ names this resultant; it is supplied by real interactions such as tension.
Guided practice
Explain why “Centripetal force is an extra force added to real forces.” fails. Then construct one example that correctly applies uniform circular-motion kinematics and force.
Independent practice
A car rounds a flat curve of radius 45 m at 12 m s⁻¹. Find its centripetal acceleration and identify the real force that supplies it.
Return to the recorded repair plan when the explanation and application are secure enough to re-test.