7. A car travels at 25 m/s to the North. It has an acceleration of 2 m/s to the south for duration of twenty seconds. What is the final velocity of the car?

It is either a  proton or a neutron im almost positive. hope this .

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)