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下列叙述正确的是（） A．滑动摩擦力阻碍物体的相对运动，一定做负功 B．物体做曲线运动动量一定变化，加速度不一定变化 C．牛顿发现万有引力定律并...

Mar 19, 2024

下列叙述正确的是（） A．滑动摩擦力阻碍物体的相对运动，一定做负功 B．物体做曲线运动动量一定变化，加速度不一定变化 C．牛顿发现万有引力定律并测定了引力常量 D．电场中电场线密的地方电场强度越大，电势一定越高

Solution

Analyze choice A: 滑动摩擦力 (kinetic friction) does oppose relative motion, but it can do positive work if the force applied to move the object is greater than the friction force, causing the object to accelerate

Analyze choice B: 物体做曲线运动 (an object in curved motion) does have a changing momentum due to the change in direction, but acceleration can be constant, such as in uniform circular motion

Analyze choice C: 牛顿 (Newton) did not measure the gravitational constant; it was measured by Henry Cavendish after Newton's time

Analyze choice D: 电场中电场线密的地方 (regions where electric field lines are closer together) indicate a stronger electric field, but the electric potential is not necessarily higher; it depends on the direction of the field relative to the point of reference

Key Concept

Electric Field and Electric Potential: The density of electric field lines represents the strength of the electric field. Electric potential, however, is related to the work done in moving a charge within the field and does not solely depend on the field strength.

Explanation

Choice D is correct because it accurately describes the relationship between electric field line density and electric field strength. The part about electric potential is not relevant to the correctness of the statement regarding electric field strength.