The ball with mass ma and MB is connected with light spring L1 and L2 with stiffness coefficient K as shown in the figure. When the two springs are at rest, the elongation is X1 and X2 respectively, then () A. As long as Ma = MB, there is X1 = x2b. As long as Ma > MB, there is X1 < X2C. As long as Ma < MB, there is X1 < x2d. As long as it does not exceed the elastic limit, there is always X1 > x2
The force analysis of ball B shows that ball B is balanced by the elastic force of gravity spring L2, and the elastic force of spring L2 is F2 = MBG. The force analysis of ball a shows that ball a is balanced by gravity and the downward elastic force of L2, and the upward elastic force of L1 is F2 and F1
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- 1. A. B: the mass ratio of the two objects Ma: MB = 1:2. Connect them with a spring without mass and place them on a smooth horizontal plane. Object a leans against the fixed plate, as shown in the figure. Push object B to the left and compress the spring. When the external force does work W, the external force is suddenly removed. After object a starts to move, the maximum elastic potential energy of the spring is () A. W3B. W2C. 2W3D. W
- 2. As shown in the figure, the bullet with mass m penetrates horizontally at velocity V0 and is placed on a smooth horizontal plane The bullet with mass m penetrates horizontally at velocity V0 on a smooth horizontal plane If the block mass m, the bullet mass m or the bullet initial velocity V0 changes, but the bullet can still pass through the block, then (assuming that the resistance of the block to the bullet and the block length remain unchanged) () A. If M remains the same, m becomes smaller and V0 remains the same, the kinetic energy obtained by the block will certainly increase B. If M becomes smaller, m remains unchanged, and V0 remains unchanged, the kinetic energy lost by the bullet must be smaller C. If M is constant, M is constant, and V0 is smaller, the kinetic energy obtained by the wood block must be constant D. No matter how V0, m and M change, the mechanical energy loss of the system will remain unchanged
- 3. As shown in the figure, the bullet with mass m hits the wooden block m resting on a smooth horizontal plane at the speed V0, and the average resistance of the bullet in the wooden block is f, The velocity of the bullet is v 1 after shooting through the block
- 4. A bullet with mass m hits a wooden block with mass m resting on a smooth horizontal plane with velocity v0. The average resistance of the bullet in the wooden block is f, and the velocity of the bullet after penetrating the wooden block is V1. Find out (1) the velocity of the bullet penetrating the wooden block and (2) the displacement of the wooden block
- 5. 3. The square block with mass m and thickness d is statically placed on a smooth horizontal plane. As shown in the figure, a bullet with mass m penetrates the block horizontally at the initial velocity V0, and the resistance of the bullet is f and remains unchanged. In the process of the bullet penetrating the block, the displacement of the block is L. what are the velocities of the bullet and the block after the bullet passes through the block?
- 6. On the smooth horizontal plane, two blocks a and B with the same mass m and thickness d are arranged side by side. A bullet C with mass m shoots at the two blocks at the horizontal velocity v0 On the smooth horizontal plane, there are two identical blocks a and B with mass m and thickness d side by side. A bullet C with mass m shoots at two blocks with horizontal velocity v0. The velocity of the bullet after passing through the first block a is V0 / 2. The bullet is finally embedded in the second block B. what is the final velocity of the two blocks
- 7. When the mass of the bullet is m, the displacement of the bullet and the block relative to the ground is S1 and S2 respectively, then S1: S2 () A. M+2mmB. 2M+mMC. M+mmD. Mm
- 8. a. B and C are the same three fast wood blocks, which are fixed on the horizontal plane side by side. When a bullet is fired along the horizontal direction, it can just shoot through the three wood blocks The time ratio of the three pieces of wood
- 9. As shown in the figure, the bullet with mass m penetrates the wood block on the smooth horizontal ground horizontally at the speed of V 0. The length of the wood block is l, the mass is m, and the resistance of the wood block to the bullet is constant. After the bullet passes through the wood block, the kinetic energy of the wood block is EK. If only the mass of the wood block or bullet changes, but the bullet can still pass through the wood block, then () A. If M is constant and M becomes smaller, the kinetic energy obtained by the wood block will certainly increase. If B. m is constant and M becomes smaller, the kinetic energy obtained by the wood block may increase. If C. m is constant and M becomes smaller, the kinetic energy obtained by the wood block will certainly increase. If D. m is constant and M becomes smaller, the kinetic energy obtained by the wood block may increase
- 10. When the wood block with mass m = 3M is fixed on a smooth horizontal plane, a bullet with mass m is fired into the wood block along the horizontal direction at the velocity V0, and the velocity of the bullet passing through the wood block is V03; now when the same wood block is placed on a smooth horizontal plane, and the same bullet is still fired into the wood block along the horizontal direction at the velocity V0, the bullet () A. It can't shoot through the wood block, the bullet and the wood block move at the same speed. B. It can shoot through the wood block. C. It can just shoot through the wood block, and the speed of the bullet is 0d. It can just shoot through the wood block, and the speed of the bullet is greater than V03
- 11. As shown in the figure, a and B balls with mass ma and MB are connected by light spring, a ball is suspended by string, and both balls are in a static state. If the string hanging a ball is cut off, what are the instantaneous accelerations of a and B balls at this time?
- 12. Two small balls a and B with mass ma and MB are respectively connected to both ends of the spring, and the B end is fixed on a smooth inclined plane with an inclination of 30 ° by a thin line If the mass of the spring is not taken into account, the accelerations of balls a and B are 0 and [(MA + MB) / MB] · g / 2. B ball, I don't understand. How to analyze the force on the spring?
- 13. As shown in the figure, on the inclined plane with an inclination angle of α, put a small ball with a mass of M, and the ball is blocked by a vertical board. Without friction, what are the pressures of the ball on the baffle and the inclined plane?
- 14. A long board with mass of M and length of L is placed on a smooth horizontal plane, and a small block with mass of M is placed at the rightmost end of the board Now add a horizontal constant force F to the right end of the long board, so that the long board is pulled out from under the small block, and the dynamic friction coefficient between the small block and the long board is μ, so as to find the work done by the horizontal constant force F to pull out the long board
- 15. A long board of mass m is placed on a smooth horizontal surface A long board with mass m is placed on a smooth horizontal plane. A slider with mass m slides along the board surface from point a to point B at a certain speed v. it advances L on the board while the board advances S. if the dynamic friction coefficient between the slider and the board is μ, how much work does the friction force do to the slider and the board?
- 16. As shown in the figure, the two boards are sandwiched in the middle by baffles, and their masses are all m. calculate the friction between them
- 17. On the ceiling, there are four balls with the same electric quantity, a, B, C and D, suspended by insulated thin wires. A and B are negatively charged, C and D are positively charged. They are close to the positively charged object M. affected by the charged body m, the thin wires deflect, as shown in the figure (1) By observing the sacrificial deflection of ball a and ball B, we can draw the following conclusions (2) By observing the sacrificial deflection of the C and D balls of the system, we can draw the following conclusions (2) Compare the string deflection angle of a, B or C, D balls, what rule can you guess?
- 18. Hang two balls a and B at the same point o on the horizontal ceiling with two thin wires of the same length, connect two balls a and B with the same length, and then apply force F on ball a, as shown in the figure. At this time, the three thin wires are in a straight state, and ob thin wire is just in the vertical direction, and the two balls are in a static state. Regardless of the size of the ball, the possible direction of force F is zero Xiang Wei () A. Horizontal right B. vertical up C. along o → a direction D. along B → a direction
- 19. The upper end of a light spring is fixed on the ceiling of the elevator, and an object is suspended at the lower end When the elevator is stationary, the spring elongation is 8 cm; later, it is found that the spring elongation is 12 cm. According to this, the movement of the elevator at this time may be () A. the acceleration is g / 2 B. The acceleration is g / 2 C. The acceleration is 3G / 2
- 20. The elevator is suspended with a spring scale on the ceiling, and a small ball is hung under the spring scale. When the elevator moves, the reading of the spring scale becomes larger Then why is the elevator moving downward to make uniform deceleration or upward to make uniform acceleration