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# M1 dynamics question watch

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1. Two particles P and Q of mass 2 kg and 3 kg respectively are connected by a light inextensible string. The string passes over a small smooth pulley which is fixed at the top of a rough inclined plane. The plane is inclined to the horizontal at an angle of 30°. Particle P is held at rest on the inclined plane and Q hangs freely on the edge of the plane with the string vertical and taut. Particle P is released and it accelerates up the plane at 2.5m s−2. Find

a the tension in the string, T = 21.9

b the coefficient of friction between P and the plane,

c the force exerted by the string on the pulley.

Could someone please go through parts b and c?
And if there is a method/rule for part c on all questions that ask this please let me know!
2. (Original post by snoopyx)
Two particles P and Q of mass 2 kg and 3 kg respectively are connected by a light inextensible string. The string passes over a small smooth pulley which is fixed at the top of a rough inclined plane. The plane is inclined to the horizontal at an angle of 30°. Particle P is held at rest on the inclined plane and Q hangs freely on the edge of the plane with the string vertical and taut. Particle P is released and it accelerates up the plane at 2.5m s−2. Find

a the tension in the string, T = 21.9

b the coefficient of friction between P and the plane,

c the force exerted by the string on the pulley.

Could someone please go through parts b and c?
And if there is a method/rule for part c on all questions that ask this please let me know!
Forces on P:
Friction from the plane, = R= mg cos30
Tension from the string =T

T- R= ma (this is the general method)
then solve for .

for c) consider direction and magnitude of tensions of the string at the points where it meets the pulley. add vectorially.
3. (Original post by snoopyx)
Two particles P and Q of mass 2 kg and 3 kg respectively are connected by a light inextensible string. The string passes over a small smooth pulley which is fixed at the top of a rough inclined plane. The plane is inclined to the horizontal at an angle of 30°. Particle P is held at rest on the inclined plane and Q hangs freely on the edge of the plane with the string vertical and taut. Particle P is released and it accelerates up the plane at 2.5m s−2. Find

a the tension in the string, T = 21.9

b the coefficient of friction between P and the plane,

c the force exerted by the string on the pulley.

Could someone please go through parts b and c?
And if there is a method/rule for part c on all questions that ask this please let me know!
I wanted to ask that are u able to solve the C part of this ques? If yes so Pls lemme know, i tried many ways but the answer ain't coming, which is at the back of book!

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