syllll_213 said:
HI, when I looked at this question, I thought that due to the acceleration, we should conclude that there is an overall force acting on that direction, and therefore the two bodies will accelerate.
That is correct.
Car and truck accelerate at exactly the same rate.
As "the mass of the truck is much greater than the mass of the car", much greater force will be required on the truck than on the car to reach the same acceleration in both bodies.
syllll_213 said:
And since the car is the only with functional battery, it should exert greater force? Am I wrong at looking at them separately?
That is also correct, if you are comparing the force exerted by the nose of the car when pushing the truck and the force exerted by the nose against the air (car accelerating alone with no truck in its way).
For accelerating only the car (little mass), the maximum possible torque from the engine will induce a greater acceleration than it would for accelerating car plus truck (much greater combined mass).
For accelerating only the car:
-Certain inertial resistance is opposing the torque of the engine from the center of mass of the car.
-No inertial resistance is exerted against the nose of the car.
For accelerating the car and the truck simultaneously:
-Same certain inertial resistance is opposing the torque of the engine from the center of mass of the car.
-Additional and greater inertial resistance is exerted against the nose of the car (transferred to that contact point from the center of mass of the truck.
Note that the second case could be idealized as a single body, or only one car of four axes having a greater mass (equivalent to the combined masses of original car and truck).
In such idealization, the point of contact between car nose and truck rear in our peoblem would behave, regarding internal forces and acceleration, just like any other point along our four axes bigger car.