When the car runs at a constant speed on a straight road with rated power, the driver reduces the throttle at T1, so that the output power of the car is immediately reduced by half, and the car continues to run at this power. At T2, the car starts to move in a straight line at a constant speed (assuming that the resistance of the car in the whole process remains unchanged), then it will move in the period of T1 < T < T2 () A. The traction of the car increases gradually B. the traction of the car decreases gradually C. the speed of the car increases gradually D. the speed of the car decreases gradually

When the car runs at a constant speed on a straight road with rated power, the driver reduces the throttle at T1, so that the output power of the car is immediately reduced by half, and the car continues to run at this power. At T2, the car starts to move in a straight line at a constant speed (assuming that the resistance of the car in the whole process remains unchanged), then it will move in the period of T1 < T < T2 () A. The traction of the car increases gradually B. the traction of the car decreases gradually C. the speed of the car increases gradually D. the speed of the car decreases gradually

When the car runs at a constant speed, the traction is equal to the resistance; when the power is reduced by half, the speed of the car has no time to change due to the inertia. According to the formula P = FV of the relationship between power and speed, the traction is reduced by half, which is less than the resistance. The resultant force is backward, and the car decelerates. According to the formula P = FV, when the power is fixed, when the speed is reduced, the traction

Using inflated balloon as the power of the car

Newton's third law of Mechanics (Law of action and reaction)
When the inflated balloon deflates, the balloon will have a force on the air. According to the third law of Newton mechanics, the air will also have a reaction force on the balloon. Therefore, the balloon net deflates in the opposite direction, and the balloon and the car are connected together, so the natural car moves with it

Junior high school physics knowledge kinetic energy and potential energy, the motion of the car has kinetic energy, this sentence is correct, then, the car has energy, this sentence is right? Is not any object has energy!

Yes, objects used to have energy
From the macro point of view: as long as the object moves, it has kinetic energy. As long as the selected zero potential energy is not on the same plane as the object you are considering, it has potential energy, but whether the potential energy is positive or negative
From the microscopic point of view: there are kinetic energy and potential energy between molecules. Kinetic energy is determined by temperature, while potential energy is determined by the distance between molecules. And kinetic energy and potential energy can not be zero

What physical knowledge does steam car use

Energy conversion (internal energy to mechanical energy)
Lever principle
Force is the cause of changing the state of motion of objects