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# Mechanics Unit 3 Edexcel - Exercises Help Watch

1. Hey guys, its been some time since i ve sitted M3 and thats why i found 3 exercises from past papers that made me stuck. I need your help .p :
1)Find x when P has been moving for 2 seconds:
What is given is mass = 0.5 kg, body is moving in positive x-axis,it moves away from O under the force of magnitude (3/(x+1)^3 )Newton and the speed of P is v
Also in first part we proved that v^2=6-(6/(x+1)^2), and in second part that the body never reaches 6^(1/2). THis is the third part

2)Actually i need the shape of this exercise :A particle P of mass m is attached to one end of a light inextendible string of length a. The other end of the string is attached to a fixed point O. The particle is released from rest with the string taut and OP horizontal.

a) Find the Tension in the string when OP makes an angle 60 degrees with the downward vertical

--> So at the beginning it says its horizontal and then vertical ?

3)ok what happens when a string slacks ? I mean tension is zero right? In this exercise , ok wait i will copy exercise here, i need b part

A particle P of mass m lies on a smooth plane inclined at an angle 30º to the horizontal.
The particle is attached to one end of a light elastic string, of natural length a and
modulus of elasticity 2mg. The other end of the string is attached to a fixed point O on
the plane. The particle P is in equilibrium at the point A on the plane and the extension
of the string is 0.25 a. The particle P is now projected from A down a line of greatest slope
of the plane with speed V. It comes to instantaneous rest after moving a distance
0.5 a.
By using the principle of conservation of energy,
(a) find V in terms of a and g,
(b) find, in terms of a and g, the speed of P when the string first becomes slack.

I found A

2. (Original post by Neofytos)
Hey guys, its been some time since i ve sitted M3 and thats why i found 3 exercises from past papers that made me stuck. I need your help .p :
1)Find x when P has been moving for 2 seconds:
What is given is mass = 0.5 kg, body is moving in positive x-axis,it moves away from O under the force of magnitude (3/(x+1)^3 )Newton and the speed of P is v
Also in first part we proved that v^2=6-(6/(x+1)^2), and in second part that the body never reaches 6^(1/2). THis is the third part
Put the RHS over a common denominator. Expand the numerator. Make v the subject.
You have separable variables, so integrate (it looks nasty, but if you've done it right, it's easier than it looks).
3. (Original post by ghostwalker)
Put the RHS over a common denominator. Expand the numerator. Make v the subject.
You have separable variables, so integrate (it looks nasty, but if you've done it right, it's easier than it looks).
il try thx

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