a ticker timer that was used, ticked dots off onto the tape at a frequency of 50Hz. What does this mean ​

250✖️100 to get you answer

Ke reqd to move from 0 to 50 will be proportional to 50x50 or 2500. this is equal to w.  to change vel from 50 to 150 you need energy prop to 22500 - 2500 = 20,000. this corresponds to 8w.  best answer is a) . work reqd is prop to velocity squared. 

Iwould think it is temperature, silica, oxides (gases)