# Special Relativity: Dynamics

### Problems on Energy and Momentum

Problem : What is the energy of a particle with mass 3.2×10-27 kilograms and velocity 0.9c ?

Problem : A particle has a momentum with magnitude 1.2×105 kgm/s and energy 4.42×10-11 Joules. What is its mass?

Problem : Two protons approach each other from opposite direction, traveling with equal and opposite speeds 0.6c . The collide to form a single particle that is at rest. What is the mass of this particle? (The proton mass is 1.67×10-27 kilograms).

Problem : A particle of mass m and speed v approaches an identical particle at rest. The particles stick together to form larger particle with mass M. What is the speed of the larger particle after the collision?

Problem : Two particles with equal mass m approach each other with speed u . They collide to form a single particle with mass M , which is at rest. Show the energy is conserved in the frame of the M particle.

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