Three question pulley set questions Preview for junior high school

The first figure is 2 strands, because one of them is a fixed pulley, so it is 1 2, this depends on how many segments there are next to the pulley, it is very easy. This should be directly looked at the moving pulley, the fixed pulley is not labor-saving so ignore, the rope at both ends of the moving pulley, so 1 2

The second figure is 1 3, three sections, as for this 1 3, for the hand, the fixed pulley is a movable pulley, and the movable pulley is a fixed pulley.

The third graph velocity is that the standard algorithm still directly divides the object velocity by the number of rope segments, i.e. 5 2=

Carp, thank you for your question, please don't**.

If you have any questions in the future, you can directly find me, and the message on the site is.

And you give 100 points too much.,It's not me who said.,You go to the post bar forum to ask someone about it.。

I'm a junior high school graduate in 09, and I'm looking for something to do.

1, f should be 1/2 of the weight, f = the number of ropes above the pulley except for the weight, 2 in the native.

2, is 3, the principle can be the fixed pulley, imagine the moving pulley, the moving pulley, people, hanging plate as the fixed pulley, so that the moving pulley, is 3 ropes.

3. The speed at which the object b moves with the movable pulley is, and above b are 2 ropes, so it needs to be divided by 2

The first diagram shows 2 strands, f=g 2 without counting the weight of the pulley.

The second question is for the hand, the fixed pulley is a movable pulley, and the movable pulley is a fixed pulley, so it is 3 strands.

The third question is, because here object a is equivalent to f, then v=v1 n=5cm s 2=

For the analysis of the moving pulley below, because the object is lifted slowly, the tension force of the chain on both sides of it is equal, and the tension on each side is equal to half of the gravity of the object. i.e. f left f right

Then analyze the above axle: on the left side of the wheel there is a downward pull f left, on the right side of the wheel there is a pull f (to be found), on the right side of the shaft there is a pull f right (on the left side of the shaft there is no tension chain loose).

From the equilibrium condition of the axle f, left*r, fright*r*r, f*r, the required force on the right side of the wheel is f (f, left*r, fright*r) r

i.e. f( r ) r g*(r r) 2 r ).

I want to know the answer, I haven't done it for a long time, is it g 2

Both pulleys are fixed pulleys. Because the two ropes of the small pulley are connected to the rope on one side of the large pulley, so that the total weight on the wooden board is equal to being pulled by the rope of 4 small pulleys, so the table scale indicator is (500+100+100) 4=175N; The spring scale is (500+100+100+100) 2=400n; The ceiling pulls the rope (500 + 500 + 100 + 100 + 100) = 1300N.

The fixed pulley weighs 500 N, the movable pulley weighs 100 N, the person weighs 500 N, the plank weighs 100 N, the bench scale weighs 100 N, the table scale indicator is N, the spring dynamometer shows 400 N, and the ceiling pulls the rope 1300 N.

Taking people, wooden boards, scales, and movable pulleys as the research objects, the spring dynamometer shows the number of f1 people pulling force on the rope f2 f1=2f2+g movement.

f1 + 2 f2 + g motion = 100 + 500 + 100 + 100 f1 = 400n ceiling pull f of the rope

f=500+500+100+100+100=1300n

o( o hahahaha hahaha, it's really funny to draw a crack wide.

1) G total = NF = 3 * 200 = 600N

G wheel = g total source Wang - g matter = 600n-480n = 120n2) v = s t = nl t = 2 * 3m 20s = 3) g total = 600n + 150n = 750n

f=1 ngTotal =1 3*750n=250nBy the way, you're drawing the wrong wheel. The rope and animation reincarnation fall.,Will hit Hengliang people.。。。

The junior high school students answered).

If the weight rises by 2m, it will move from the end of the core to move 4m.

fs=200*4=800

1) The potential energy increased by the weight and the movable pulley together = work done.

g+g0) 2=800 g0=-80 pickpockets are written incorrectly, and the moving pulleys are floating.

Anyway, the idea is this.

2）v=s/t=4/20=

3）150/2+f

As can be seen from the figure, the tensile force of the rope hanging from the platform is 4f, and the person and the platform are touched as the whole side inclusion, and the resultant force is 0.

Then 4f f g person g g runway.

F (G people laughing at the G platform) 5 (500 100) 5 120 Ox.

220 and 198

The tensile force of each strand of rope connected to the movable pulley is the same, equal to 1 n of the weight of the object they lift (n represents the number of strands of rope connected to the movable pulley) The object they are lifting is the movable pulley and the object underneath, so f=1 3(600N+60N)=220N

The work done by the pulling force is equal to the pulling force multiplied by the distance traveled by the self-propelled end of the rope, and the distance traveled by the free end of the rope is equal to n times the rising height of the object, so w=f*s=f*nh=220n*3*

The first empty solution process: since the friction and the weight of the rope are not counted, the rope on both sides of the pulley is equal According to the principle of equilibrium force (the object is raised at a constant speed), from this the equation can be listed:

f+2f==600+60 then f=220n, then spring reading=220n

The second empty-air solution process: regardless of friction and rope weight, then the efficiency of pulling f is 100%, then w=(600+60)*

The spring scale in this diagram measures the tension of the rope, and there is no need to consider the problem of the rope being pulled to both sides (just like measuring the weight of an object with a spring dynamometer, there are two forces, but in fact only one has an effect).

So the spring dynamometer has an indication of f, which is 220N, and the work done is 198j

The question option is wrong.

Figure A has 2 strands of rope on the movable pulley, so F A = (600 + 30) 2 = 315n The same goes for Figure B, Figure B has 3 strands, so F B = (600 + 30) 3 = 210n If there is something you don't understand, you can ask me, and I will continue to answer.

How do I feel that none of them are right, B is to save three times the force, that is, two hundred N, plus two pulleys is up to 260?