《牛顿第定律》课件

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,1.What is a force?,2.What can forces do?,Newtons First Law of Motion,牛顿第一定律,牛顿第一定律,一切物体在没有受到外力作用的时候，总保持匀速直线运动状态或静止状态。,一切物体,没有受到外力作用,总保持,An object maintains its state of rest or constant velocity motion unless it is acted on by an external unbalanced force.,Newtons First Law of Motion,力和运动的关系：,力不是维持物体运动的原因，而是,改变物体运动状态,的原因。,What can forces do?,一切物体都具有保持静止,(at rest,),或匀速,(constant velocity),直线运动状态的性质。,牛顿第一定律表明：,物体具有保持原来匀速直线运动或静止状态的性质，我们把这种性质叫做,惯性,inertia,。,牛顿第一定律也称惯性定律,law of inertia,情境模拟,Inertia,More massive objects are harder to move than less massive objects,All matter has mass, inertia, gravity,More mass = more gravity = more inertia,Less mass = less gravity = less inertia,牛顿第二定律,Newtons Second Law of Motion,Explain how change in motion relates to,unbalanced,forces,Newtons Second Law of Moti,on,Balanced Forces,Unbalanced Forces,Balanced Forces,When all forces equal each other, we have balanced forces.,Moving objects wont accelerate or decelerate,Moving objects wont change direction,Not moving objects will remain at rest,Unbalanced Forces,When one force is greater than the other forces,A moving object can accelerate or decelerate,Moving objects can change direction,Moving objects can stop moving,Not moving objects can start to move,作用在一个物体上的加速度与作用在物体上的力成正比，与物体的质量成反比。,Newtons Second Law of Moti,on,The acceleration of an object varies in direct proportion to,the external unbalanced force,applied to it and inversely proportional to its mass.,Mathematically:,a F and a ,1/,m,An unbalanced force of 48 N west is applied to a 6.0 kg cart. Calculate the carts acceleration,A car of mass 2000 kg decelerates from 30 m s,1,to rest in a distance of 100m.Calculate the retarding force required to stop the car.,再见,