Amoving electron has kinetic energy k1. after a net amount of work w has been done on it, the electron is moving one-quarter as fast in the opposite direction. (a) findw in terms of k1

15/16 k₁

Explanation:

k₁= 1/2 mv₁² is where k₁ is the kinetic energy of the electron before the work is done

K₂ = 1/2 m(-v₂)² after the work has been done

also given

v₂ = - v₁ / 4

substitute v₂  into the formula for K₂

k₂ = 1/2m (  - v₁ / 4)²

k₂ = 1/2mv₁²/16 = 1/16 k₁

work done on the electron according to work- energy theorem is equal to the change in the kinetic energy of  the electron

i don't understand. explain it clearly

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg