Law of conservation of mechanical energy The trolley with mass m and length L stops on a smooth horizontal plane, and the small block with mass m is placed on the leftmost end of the trolley. Now, a right water balance force F is applied on the small block to make the block move uniformly and linearly from the static state. The friction force between the block and the trolley is f '. When the block slides to the rightmost end of the trolley, the distance of the trolley is s. in this process, when the block slides to the rightmost end of the trolley, the distance between the block and the trolley is s, Is the added mechanical energy of block and trolley FS? Why?

Law of conservation of mechanical energy The trolley with mass m and length L stops on a smooth horizontal plane, and the small block with mass m is placed on the leftmost end of the trolley. Now, a right water balance force F is applied on the small block to make the block move uniformly and linearly from the static state. The friction force between the block and the trolley is f '. When the block slides to the rightmost end of the trolley, the distance of the trolley is s. in this process, when the block slides to the rightmost end of the trolley, the distance between the block and the trolley is s, Is the added mechanical energy of block and trolley FS? Why?

For the force analysis of M, the resultant force is f-f ', and the displacement is L + s
E = (f-f ') (L + s)
For the force analysis of M, the resultant force is f ', and the displacement is s. The kinetic energy theorem is used
We get e = f '* s
The initial kinetic energy of the system is 0
The final kinetic energy is
M kinetic energy + m kinetic energy
The increased mechanical energy is: FL + fs-f '* L

Using the law of conservation of mechanical energy
Someone throws a small ball with a mass of 0.5kg from a balcony 22.5m above the ground. If the kinetic energy of the ball when it lands is 9 times that when it is thrown, what is the speed of the ball when it is thrown?
Please write the calculation process,

Halo, this is so simple, the ball landing is only potential energy into kinetic energy
0.5*22.5*g+0.5*0.5v*v=0.5*0.5*v*v*9
solve equations
If G is 10, v = 7.5

In the experiment of using free falling motion to verify the law of conservation of mechanical energy: if the instantaneous velocity is calculated and verified by measuring the distance between two points on the paper tape, the distance between point 2 and point 4 is S1, the distance between point 0 and point 3 is S2, and the period of tapping is t The relation of T = 0___ ．

According to the deduction of uniform variable speed linear motion, the velocity v = s12t when striking point 3, the height h = S2 when the weight falls, when the mechanical energy is conserved, there should be 12m (s12t) 2 = mgs2, thus t = s218gs2; so the answer is: s218gs2