A mass M travels around a horizontal circle at uniform speed v. What happens to momentum and kinetic energy when it reaches a diametrically opposite point?
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A mass M travels around a horizontal circle at uniform speed v. What happens to momentum and kinetic energy when it reaches a diametrically opposite point?

G1 Physics · Accepted Answer

Step 1 — Principle: In uniform circular motion, centripetal force is perpendicular to the instantaneous velocity. Step 2 — Working: At opposite points velocity vectors are oppositely directed, so Δp=M(−v−v)=−2Mv along tangent, magnitude 2Mv. Step 3 — Working: Speed and KE remain unchanged. Correct answer: C — Momentum changes in magnitude by 2Mv.