Question

An unstable particle with a mass equal to 3.34 ✕ 10−27 kg is initially at rest. The particle decays into two fragments that fly off with velocities of 0.971c and −0.851c, respectively. Find the masses of the fragments. (Hint: Conserve both mass–energy and momentum.) m(0.971c) = kg m(-0.851c) = kg

Answer 1

Given the initial mass m = 3.34 x 10-27kg and it is at rest. So the initial velocity u = 0. The particle decays into two parts of masses m1 and m2 with velocities v1 = 0.971c and v2 = -0.851c respecttively.

Since mass is conserved,

The initial momentum of the system is,

The final momentum of the system is,

By law of conservation of momentum,

So the masses of the fragments are 1.56 x 10-27kg and 1.78 x 10-27kg.