题目

一带电小球在空中由A点运动到B点的过程中，受重力、电场力和空气阻力三个力作用。若重力势能增加3J，机械能增加0.5J，电场力做功1J，则小球A．重力做功为3J B．电势能增加1J C．克服空气阻力做功0.5J D．动能减少2.5J 答案：CD看图，回答下列问题（1）What's the weather like? _______________________ （2）Is it raining heavily? _______________________ （3）Do the people go home quickly or slowly? _______________________ （4）Does the wind blow strongly? _______________________（5）Can you go out and play? _______________________