Which is most likely a physical change

a. cutting a substance into four pieces
b. burning a substance into ash and smoke
c. reacting a substance chemically to form a new substance
d. combining a substance with water to make rust

An electron in a television tube is accelerated uniformly from rest to a speed of 8.4\times 10^7~\text{m/s}8.4×10 7 m/s over a distance of 2.5 cm. what is the instantaneous power delivered to the electron at the instant that its displacement is 1.0 cm?