Huangpu sports center to Huangpo New Village
The first sentence (must be understood): " centripetal force is the resultant force " "
if you don't understand this sentence, it's useless to say anything
the second sentence (be sure to remember): " force determines speed, not speed determines force " "
the reason why an object can do uniform circular motion is that the centripetal force just" supports "the object to complete uniform circular motion
if the force is large, the object will be close to the center of the circle; If the force is small, the object will be far away from the center of the circle This sentence, it seems, we all know)
the problem in the exam is often that the speed is known and the force needs to be sought (for example, just passing the highest point of the ring, that is to say, when passing the highest point, the speed is zero); If you do too many questions like this, it will give you the illusion that speed is decisive
Answer your question:in the figure below, FN is the ideal train force, and FN is the resultant force of supporting force and gravity
the resultant force just "supports" the uniform circular motion of the train. Therefore, there is no friction trend between wheel and track at this time! There is no friction
the probability of the examination questions will be as follows: given the train speed, train weight and the inclination angle of the rail, calculate the lateral supporting force between the rail and the wheel
solution: obtain the centripetal force from the speed, subtract the gravity component, and get the supporting force of the rail to the train (at this time, it may not be perpendicular to the contact surface, if you don't understand, you can ask, and if you explain more, you will deviate)
Doesgive people another illusion of speed determining power If the speed continues to increase and the track can't hold, will the train overturn In fact, it's the force of the track on the wheel that makes the train move in a circle It's not necessarily uniform. If you don't understand, you can ask
Second, the inner rail is stressedwhen the train is stationary on an inclined track, no centripetal force is needed. Why didn't the train slide off the track? The inner rail gives the wheel an outward force
If you think about these two things clearly, the following problems will be solved
by the way, the reason why the rail should be tilted when turning is to let the base surface of the rail provide centripetal force as far as possible, rather than the edge between the rail and the wheel
I guess the railway designer sets the inclination angle of the rail according to the "turning curvature" of a certain section of railway and the "rated running speed of the train" of the section
the market value of Sony's "book value" is about 40 billion US dollars http://finance.cn.yahoo.com/q/o?s=sne
however,
the total assets of Sony Group: 357 billion US dollars (1. The global market value of the group: 137 billion US dollars. 2 Group Global Fixed Assets: US $103 billion. 3. Group global liquidity: US $17 billion. 4. Group global brand value: US $100 billion)
although the book has shrunk after a long time ~ ~ ~ the actual value can not be seen only in the book~~~
CNC milling machine is a kind of automatic processing equipment developed on the basis of general milling machine. The processing technology and structure of the two machines are basically the same. CNC milling machines are divided into two categories: without tool magazine and with tool magazine. The CNC milling machine with tool magazine is also called machining center.