If an object with a mass of 5 kg changes speed from 12m/s to 8m/s, by how much does its kinetic energy change? Physics Work and Energy Energy 1 Answer ali ergin Apr 6, 2016 Delta E_k=-200 J Explanation: "data :" m=5" kg 'mass of object'" v_i=12" m/s ' initial velocity of object'" v_l=8" m/s 'final velocity of object'" E_k=1/2*m*v^2" The kinetic energy of object" E_i=1/2*5*12^2 E_i=(5*144)/2 E_i=360 " J the initial kinetic energy of object" E_f=1/2*5*8^2 E_f=5*64/2 E_f=160 " J the final kinetic energy of object" Delta E_k=E_f-E_i Delta E_k=160-360 Delta E_k=-200 J Answer link Related questions How do matter and energy interact? Question #50ca2 Question #242cf Question #5038d Question #50391 What is potential energy? Question #d6576 Question #50cae Question #50cb2 Question #50cb6 See all questions in Energy Impact of this question 1752 views around the world You can reuse this answer Creative Commons License