The left end of the wood block with mass m (which can be regarded as a mass) is connected with a light spring, and the other end of the spring is connected with a baffle fixed on a large enough smooth horizontal table The left end of the wood block with mass m (which can be regarded as a mass point) is connected with a light spring, the other end of the spring is connected with a baffle fixed on a large enough smooth horizontal table, the right end of the wood block is connected with a light thin line, which bypasses the smooth light pulley without mass, and the wood block is in a static state. In the following cases, the spring is within the elastic limit, regardless of air resistance and line deformation, The acceleration of gravity is g (1) In figure a, a constant force of F is applied at the other end of the line. The block leaves the initial position o and moves to the right. The spring begins to stretch and deform. It is known that the speed of the block passing through point P is V, and the distance between two points OP is S. the elastic potential energy of the spring when the block is pulled to point P is calculated; (2) If at one end of the line, instead of applying a constant force, a hook code with mass m is suspended, as shown in Figure B, the block moves from the initial position o to the right, and the speed of the block passing through point P is calculated

The left end of the wood block with mass m (which can be regarded as a mass) is connected with a light spring, and the other end of the spring is connected with a baffle fixed on a large enough smooth horizontal table The left end of the wood block with mass m (which can be regarded as a mass point) is connected with a light spring, the other end of the spring is connected with a baffle fixed on a large enough smooth horizontal table, the right end of the wood block is connected with a light thin line, which bypasses the smooth light pulley without mass, and the wood block is in a static state. In the following cases, the spring is within the elastic limit, regardless of air resistance and line deformation, The acceleration of gravity is g (1) In figure a, a constant force of F is applied at the other end of the line. The block leaves the initial position o and moves to the right. The spring begins to stretch and deform. It is known that the speed of the block passing through point P is V, and the distance between two points OP is S. the elastic potential energy of the spring when the block is pulled to point P is calculated; (2) If at one end of the line, instead of applying a constant force, a hook code with mass m is suspended, as shown in Figure B, the block moves from the initial position o to the right, and the speed of the block passing through point P is calculated

(1) When the wood block is pulled to point P by force, let the elastic potential energy of the spring be e. according to the kinetic energy theorem
FX--E=(mv^2)/2 E=FX--(mv^2)/2
(2) When the weight is suspended, when the block moves to the point, the elastic potential energy of the spring is still E. let the speed of the block be v ',
According to the law of conservation of mechanical energy:
MGX = e + 1 / 2 (M + m) V '^ 2 V' = under root sign (2mgx -- 2fx + MV ^ 20) / (M + m)
The results are as follows
2 points