Can somebody please urgently help me with this problem? please help :(

A)Particle X has a speed of 0.750 c and a momentum of 4.86×10-19 kgm/s. What is the mass of the particle?
1.430×10-27 kg....i figured this out

B)What is the rest energy of the particle?
1.287×10-10 J....I figured this out

C)What is the kinetic energy of the particle?
I've been stuck on this problem for the last 3 hours :(

D)What is the total energy of the particle?
I need help with this one too. please help me

No, the real easiest way is to know the physics.

C. k = Pc is the kinetic energy. The momentum P = Mv was given = 4.86E-19 kg.m/s and c = 299E6 m/s. So the kinetic energy is just k = 4.86E-19*299E6 = 1.45314E-10 = 1.45E-10 J. ANS.

D. And the total energy is E = Mc^2 = (P/v) c^2 = (4.86E-19/(.75*299E6))*(299E6)^2 = 1.93752E-10 = 1.94E-10 J. ANS.

M = m/sqrt(1 - (v/c)^2), which I suspect you knew but I thought I'd better define the big M just in case.

Easiest way to do D and C is in the other order.

D: E = gamma*mc^2 where gamma = 1/sqrt(1 - v^2/c^2) = 1/sqrt(1 - 0.75^2). But you already worked out gamma for question A, right?

C: Kinetic energy = total energy - rest energy = gamma * mc^2 - mc^2.