Particle A starts from rest with acceleration 4 m s⁻². Three seconds later, particle B starts from the same point in the same direction with constant speed 24 m s⁻¹. After B starts, the first meeting occurs after:
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Question

Particle A starts from rest with acceleration 4 m s⁻². Three seconds later, particle B starts from the same point in the same direction with constant speed 24 m s⁻¹. After B starts, the first meeting occurs after:

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G1 Physics · Accepted Answer

Let t be time after B starts. A has already moved for t + 3 seconds. Thus x_A = 2(t + 3)² and x_B = 24t. Equating: 2(t + 3)² = 24t ⇒ t² − 6t + 9 = 0 ⇒ (t − 3)² = 0. Hence the meeting occurs after 3 s.