Two vehicles of mass m and 2m are moving in the same direction on a highway. both drivers apply their brakes at the same time and both vehicles begin sliding. if the coefficient of kinetic friction μk is the same for both vehicles, how do their accelerations a1 and a2 compare?

The mass is inversely proportional to the acceleration so the acceleration a1 is twice that acceleration a2

Explanation:

The force of friction and the kinetic force make the law of mass in moving so

The forces are the same however at the moment to determinate the acceleration

are constant because they make the same motion however the difference of mass make the acceleration difference

layer a is the exosphere and layer b is the thermosphere.   is the answer i think but i hope this .

that would be because of both gravity and friction. so     c