# Physics

posted by
**Qi**
.

Can you explain the solutions steps by steps? Because i really don't understand when i revise it now. Thanks. The lines CA & CB are lines of greatest slope of two smooth fixed planes that intersect in a horizontal line through C. AB is horizontal & 5

m long. BC=3m & CA=4m. Particles P & Q, having masses 0.3kg & 0.4kg respectively, are placed on CA & CB, & are joined by a light inextensible string that passes over a small pulley at C. The particles are held at rest with the string taut & are then released. Find the magnitude of the acceleration of each particle. During the motion a force of magnitude X N directed towards A is applied to P. As a result, the acceleration of P is reversed in direction but is unchanged in magnitude. Find X. Given that the force of magnitude X N is applied 0.25s after the particles are released, find the distance travelled by P before it first comes instantaneously to rest. [you may assume that P does not reach C & Q does not reach B.] answers: 1.96ms^-1 ; 2.75N ; 0.061m