Final answer:
The subject of this question is Physics, and it pertains to the motion of an axle with two wheels rolling on a downward-sloping pavement and lawn.
Step-by-step explanation:
The subject of this question is Physics. The question is asking about an axle with two wheels rolling along a downward-sloping pavement and lawn.
In Physics, the wheel and axle is a simple machine consisting of a rod fixed to the center of a wheel. When the axle rolls, the wheels also rotate, allowing the object to move. The movement of the axle and wheels can be influenced by factors such as the slope of the pavement and the lawn, as well as the force applied to the axle.
For example, if the axle is tilted downward on the pavement, the force of gravity can cause the wheels to accelerate as they roll down the slope. On the lawn, the friction between the wheels and the grass can slow down the movement of the axle. The physics behind the motion of the axle and wheels can be analyzed using concepts such as forces, motion, and energy.