MYP Physics · 04 · multiple choice
Momentum belongs to a chosen system
Momentum · Original GioPhysics question with a detailed, mark-by-mark answer guide.
- Demand
- recall
- Marks
- 3
- Topics
- 2
- Answer
- Complete
A 2.0 kg trolley moves east at 3.0 m s⁻¹ and a 1.0 kg trolley moves west at 4.0 m s⁻¹. Take east as positive. What is the total momentum of the two-trolley system?
- A
+10 kg m s⁻¹
- B
+2.0 kg m s⁻¹
- C
−2.0 kg m s⁻¹
- D
+5.0 kg m s⁻¹
- a
Select and show Select the correct total momentum and show how direction is included.
3 marks
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a
Select and show Select the correct total momentum and show how direction is included.
Predict from the governing principle before looking for a matching option. Then reject alternatives by checking direction, units, limiting behaviour or the physical meaning of each statement.
- 1
Selects option B: the system's total momentum is +2.0 kg m s⁻¹.
- 2
Calculates eastward momentum as 2.0 × 3.0 = +6.0 kg m s⁻¹ and westward momentum as 1.0 × (−4.0) = −4.0 kg m s⁻¹.
- 3
Adds signed momenta to obtain +2.0 kg m s⁻¹, meaning eastward.
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