Question

A body of mass 0.8kg has initial velocity u=4i+3j m/s and v=-6j+2k m/s find change in kinetic energy???

Answer 1

Initial kinetic energy=1/2mass×magnitude of initial velocity
=1/2×0.8×5=2J. (|u|=√4×4+3×3 =√5)
final kinetic energy=1/2×m×v=1/2×0.8×40=16J. (|v|=√6×6+2×2=√40)
change in kinetic energy=final-initial=16-2=14J

Answer 2

Answer: Initial kinetic energy=1/2mass×magnitude of initial velocity

=1/2×0.8×5=2J. (|u|=√4×4+3×3 =√5)

final kinetic energy=1/2×m×v=1/2×0.8×40=16J. (|v|=√6×6+2×2=√40)

change in kinetic energy=final-initial=16-2=14J

Hope it helps...