Final answer:
When two blocks are pushed by equal forces, if they start from rest or with the same initial velocity, their momenta will be the same. The total momentum of a system is conserved in the absence of external forces, both before and after a collision. Momentum is conserved in collisions even if kinetic energy is not, unless the collision is elastic.
Step-by-step explanation:
When two blocks with different masses are pushed by constant forces of equal magnitude, the changes in their momenta will depend on the mass and acceleration. Since the forces are equal and acceleration is inversely proportional to mass, the block with mass m will have a greater acceleration than the block with mass 2m. However, momentum is the product of mass and velocity. If the forces act over the same time, the change in velocity will be greater for the lighter block, making its final momentum equal to that of the heavier block, assuming they started from rest or with the same initial velocity.
In summary, if two blocks are pushed by equal forces for the same amount of time, and if they start from rest or the same initial velocity, option a. The momentum of the blocks is the same, is correct.
According to the conservation of momentum, the total momentum before and after a collision remains constant in the absence of external forces. This applies to car collisions and air car experiments. In scenarios where there is a collision between objects, such as the air cars or the cars bumping into each other, the total momentum of the system is conserved, as per option b. It will be equal before and after the collision.
When we analyze momentum conservation in collisions where there are no external forces, like in the case of object A moving and object B at rest, we find that after the collision, the total momentum of the system remains conserved. However, the kinetic energy may not be conserved unless the collision is elastic, aligning with option b. Momentum is conserved, but kinetic energy is not conserved.