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关于物体的运动，下面情况可能存在的是（　　） A．加速度在减小，速度在增加 B．加速度方向始终改变而速度不变 C．加速度和速度大小都在变化，加速度最大时速...

Mar 19, 2024

关于物体的运动，下面情况可能存在的是（　　） A．加速度在减小，速度在增加 B．加速度方向始终改变而速度不变 C．加速度和速度大小都在变化，加速度最大时速度最小，速度最大时加速度最小 D．加速度为负值时，物体做加速运动

Solution

Analyze choice A: Acceleration decreasing while velocity increasing is possible if the object is moving in the opposite direction to the acceleration

Analyze choice B: Acceleration direction changing while velocity remains constant is not possible because a change in acceleration direction implies a change in velocity direction

Analyze choice C: Acceleration and velocity magnitudes changing such that when one is maximum the other is minimum is not typically observed in standard kinematic situations

Analyze choice D: Negative acceleration with the object accelerating is possible if the object is slowing down in the positive direction or speeding up in the negative direction

Key Concept

Acceleration is the rate of change of velocity. It is a vector quantity, meaning it has both magnitude and direction. Negative acceleration can either mean slowing down (deceleration) if it's in the same direction as the velocity or speeding up if it's in the opposite direction.

Explanation

Choice D is correct because negative acceleration can still mean the object is accelerating, depending on the direction of the velocity relative to the acceleration.

这是道多选题

Solution

Analyze choice A: Acceleration decreasing while velocity increases is possible if the object is moving in the direction opposite to the acceleration

Analyze choice B: Acceleration direction can change while maintaining constant speed in circular motion

Analyze choice C: Acceleration and velocity can both change. However, the relationship described is not necessarily true

Analyze choice D: Negative acceleration can mean the object is decelerating, not necessarily accelerating

Key Concept

In circular motion, the direction of acceleration changes continuously as the object moves along the circle, while the magnitude of the velocity can remain constant.

Explanation

Choice B is correct because it describes uniform circular motion, where the object moves at a constant speed but the direction of acceleration (towards the center of the circle) is always changing.