بسم الله الرحمن الرحيم
1.m=mo/[1+(v/c)^2]^1/2 = 2*mo/3^1/2
the change in the mass : m-mo = (0.268/1.73) mo = 0.15 mo
then the increase in the mass : 0.15 mo / mo *100% = 15%
2. U = (u + v)/[1+u*v/c^2] , U = (0.8c + 0.5c)/[1+(0.8c*0.5c)/c^2] , U = 0.93c
3. In classical : K=1/2 * me * v^2 , 0.1*10^6*1.6*10^-19 = 1/2*9.1*10^-31*v^2 , v= 1.87*10^8 m/s
In relativity : K=m*c^2/[1+(v/c)^2]^1/2 - m*c^2 , [1+(v/c)^2]^1/2 = 8.19*10^-14 /9.79*10^-14 , v= 1.64*10^4 m/s
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