Read Recoil Throws: Reapply Momentum After Each Release
Each ball is launched at 6 m/s relative to the boat at the moment of release. Momentum conservation applies separately to each throw because the moving system mass changes after the first ball leaves.
Recoil from Sequential Throws is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Start with the condition
For simultaneous release, write the two ball speeds as V minus v-relative in the ground frame. For sequential release, solve the first event, then use its resulting boat speed as the initial state of the second.
Build the governing relation
Keep the stated relative speed relative to the boat, not to the ice. Check every stage by making total horizontal momentum zero in the original rest frame.
Finish with a physical check
Check the limiting case before selecting an option: remove the special feature in the diagram or make the relevant parameter very large or very small. The result should reduce to a familiar relation.
OlympIQ exam lens
- ✓State the physical condition before choosing a formula.
- ✓Keep direction, sign and constraint information explicit.
- ✓Test one limiting case before committing to an option.
Using the same total mass for both sequential throws treats the first released ball as though it remains on the boat.
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