A car, while traveling on a horizontal road, experiences a sudden tire blowout. Assuming the car was initially moving at a constant speed, and the driver doesn't apply the brakes immediately, which of the following best describes the immediate change in the car's kinetic energy?
答案解析
This question tests the understanding of kinetic energy, rotational motion, and the immediate effects of a tire blowout. The core concept is that kinetic energy is related to the overall speed of the car, not directly to the rotation of the wheels. The tire blowout will initially affect the rolling radius and the way in which the wheels rotate, not the vehicle's translational motion.
* **Core concept:** Kinetic energy is primarily determined by the car's mass and translational speed (KE = 1/2 * mv^2).
* **Solution:** Immediately after the blowout, the car's speed is not going to change significantly if the brakes are not applied. The change in angular velocity of the wheel and change in effective rolling radius is an immediate affect but not a direct effect on the car's linear motion, thus does not directly change the car’s kinetic energy. The blowout impacts the relationship between the wheels' rotation and the car's linear speed, but it doesn't instantly alter the car's overall speed.
* **Option A analysis (Incorrect):** Although the reduced radius *does* increase the wheel's angular velocity for a given car speed, this doesn’t directly translate to an increase in the car’s kinetic energy. The car is still moving at approximately the same speed. This is a trap focusing on the relationship between angular and linear motion.
* **Option B analysis (Incorrect):** Although the tire blowout causes a decrease in rolling radius which relates to the car’s linear motion, this change is not immediately affecting the overall speed and thus the kinetic energy. The speed of the car is maintained for the instant immediately after the blow out. This option is partially true for a later time but wrong for the “immediate” effect.
* **Option C analysis (Correct):** This is the most accurate statement. The car’s overall speed is approximately maintained (for the instant immediately after the blowout); therefore, its kinetic energy is approximately the same for the time immediately after the blow out. The rolling radius change does not immediately affect the overall speed and thus the kinetic energy.
* **Option D analysis (Incorrect):** While the location of the blowout will eventually affect the car’s direction and stability, it will not directly influence the initial change in overall kinetic energy. This is a misleading trap that involves secondary effects.
正确答案:C