Author Topic: Confusing M1 question  (Read 689 times)

Offline XaM!!

  • SF Master
  • ******
  • Posts: 1637
  • Reputation: 2680
  • Gender: Male
Confusing M1 question
« on: May 02, 2010, 10:35:52 am »
Two particles P and Q have mass 0.5 kg and m kg respectively, where m < 0.5. The particles are connected by a light inextensible string which passes over a smooth, fixed pulley. Initially P is 3.15 m above horizontal ground. The particles are released from rest

When P strikes the ground, P does not rebound and the string becomes slack. Particle Q then moves freely under gravity, without reaching the pulley, until the string becomes taut again.

e) Find the time between the instant when P strikes the ground and the instant when the string becomes taut again.

I got 6/7 s which is the right answer

But I was thinking when P hits the ground doesn't Q move up 3.15m and so i calculate the time for this and add it on to the time for the string going slack 

I've attached the question picture

Dnt walk As iF u RulE da WorLd..... Walk As if U dOnT CarE wHO RuLzz It.......



Offline astarmathsandphysics

  • SF Overlord
  • *********
  • Posts: 11271
  • Reputation: 65534
  • Gender: Male
  • Free the exam papers!
Re: Confusing M1 question
« Reply #1 on: May 02, 2010, 11:13:58 am »
No cos the acceleration is not the same - anyway it says from when P hits the ground