Two particles P and Q have masses 1.5 kg and 3 kg respectively - Edexcel - A-Level Maths Mechanics - Question 8 - 2016 - Paper 1

To find the tension in the string, we start by considering the forces acting on particle P. The weight of particle P is given by:

$R = 1.5g$

The frictional force, (F_f), acting against the motion of P is:

$F_f = \mu R = \frac{1}{5}(1.5g) = 0.3g$

Using Newton's second law for particle P, we can express the forces horizontally:

$T - F_f = 1.5a$

Substituting the frictional force:

$T - 0.3g = 1.5a$

For particle Q, which has a mass of 3 kg, we apply Newton's second law vertically:

$3g - T = 3a$

Now we have two equations:

1. (T - 0.3g = 1.5a)
2. (3g - T = 3a)

We can solve these equations simultaneously for T and a.