The external force on a body is a constant force, which starts to move from rest. The longer the force is applied, the longer the () A. The greater the instantaneous velocity of the object, the greater the instantaneous acceleration of the object, the more work done to the object in unit time, and the greater the instantaneous power of the force

A. If the combined external force is a constant force, the acceleration will be constant. According to v = at, the longer the action time, the greater the velocity. So a is correct, B is wrong. C. the work done on the object in unit time represents the average power. The average power P = F.V,. V = 0 + V2, the longer the action time, the greater the average velocity

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1. For the first time, the horizontal constant force F is applied to the object a to make the object a move a certain distance s on the smooth horizontal plane, and for the second time, the same size force parallel to the inclined plane is applied If the mass of object a is known to be less than that of object B, then Why is the increment of mechanical energy equal in two processes?
2. When an object with mass m is placed on a rough horizontal plane, its dynamic friction force is u. under the action of constant force F, it moves in the horizontal direction, and the displacement s, F and the horizontal direction a are the same Find (1) the work done by each force (2) Find the total work of these forces on the object (3) Seeking external force (4) Total work done by combining external forces
3. The mass of the object on the horizontal plane is m, and the horizontal constant force F moves L; then the external force is removed, and the object moves 2L and stops?
4. When the water balance force F acts on the object with mass m, it means to move the displacement l along the direction of the force on a smooth horizontal plane. The work done by the constant force is W1, and then use the constant force Then the force is applied to the mass m (m)
5. Under the action of constant horizontal force F1, the object on the horizontal plane moves at a constant speed V1; if the force becomes a constant oblique force F2, the object moves at a constant speed v2 And the power of F1 and F2 are the same A F1=F2,V1>V2 B F1=F2,V1F1,V1>V2 D F2
6. The object m moves forward under the action of a constant force F in the horizontal direction on a smooth plane, and a spring with enough stiffness coefficient is fixed in its forward direction When the object contacts the spring, the a. Slow down immediately b. The external force on the object first decreases and then increases c. After a short period of time, the velocity of the object reaches the maximum and the acceleration is 0 d. When the spring is in the maximum compression, the acceleration of the object is 0 Thanks a lot!
7. The object m moves on a smooth plane under the action of a constant force F along the horizontal direction, and a light spring with enough length is fixed in its forward direction When the object contacts the spring, it contacts and presses the spring to the shortest distance Block a decelerates when it contacts the spring Block B accelerates first and then decelerates when it contacts the block C when the velocity of the block is zero, the resultant force is zero D when the spring is in the maximum compression, the acceleration of the block is exactly equal to zero
8. As shown in the figure, on a smooth horizontal plane, two objects AB move under the action of constant horizontal forces F1 and F2. Given that F1 > F2, what is the force a exerts on B
9. 2. The dynamic friction coefficient between the object with mass m and the horizontal plane on the horizontal plane is μ? 2. The dynamic friction coefficient between the object with mass m and the horizontal plane is μ. Under the action of the horizontal constant force F1, the object moves in a straight line at a constant speed on the horizontal plane. Now, if a constant force F2 equal to F1 is applied to the object, what is the maximum value of the combined external force acting on the object in the process of displacement s?
10. Under the action of constant force F, the object with mass m moves in a straight line with uniform acceleration along the horizontal plane, and the angle between F and the horizontal plane is θ Under the action of constant force F, the object with mass m moves along the horizontal plane with uniform acceleration. The angle between F and the horizontal plane is θ, and the dynamic friction coefficient between the object and the horizontal plane is μ
11. Under the action of the horizontal constant force F of known size, the mass m starts to move along the horizontal plane from rest. After time t, the external force F is removed, and then the mass m comes to rest again after time 2T
12. There is an object with mass m on the horizontal plane, which is in a static state and starts to move under the action of constant force F. after time t, the external force is removed, and then after time t, the object just stops. What is the friction force on the object? What is the acceleration of the object before the external force F is removed? Two ask ha, don't copy, I don't understand them
13. Under the action of the horizontal constant force F, the object with mass m on the horizontal plane starts to make a uniformly accelerated linear motion from the static state, and the external force is removed after time t, and then the object moves after time 3T When the body stops, what is the resistance?
14. Under the action of horizontal constant force F, the object with mass m starts to move along the horizontal plane from standstill. After t, the external force F is removed, and the object stops at the center after 2T (1) The resistance of the body (2) the total displacement of the body
15. There is an object on a smooth horizontal plane. Under the action of horizontal constant force F, it starts to move from static state. After a certain period of time, its speed reaches V, and then after a period of time There is an object on a smooth horizontal plane, which starts to move from rest under the action of horizontal constant force F. after a certain period of time, the velocity reaches V, and then after a period of time, the velocity increases from V to 2V. In these two periods of time, what is the ratio of work done by external force F to the object?
16. Under the action of a horizontal constant force F, an object with a mass of m on the horizontal plane starts to make a uniformly accelerated linear motion from rest. After time t, the external force is removed, and after time 2T, the object stops. What is the resistance of the object?
17. The light spring is upright and on the horizontal table. The object a with a mass of 2kg is placed on the top of the light spring in a static state. Now the object B with a mass of 3kg is placed on the table What is the elastic force of a to B at the moment when it is placed on a?
18. A 2kg object a is placed on the light spring of the horizontal table. If a 3kg object B is placed on a lightly, the pressure of B on a is?
19. When a bullet with a mass of 10 g penetrates a board at a speed of 400 m / s and the speed becomes 100 m / s after passing through, the work done by the bullet to overcome the resistance is (1), If the thickness of the wood block is 10cm, the average resistance of the wood block to the bullet is (2) n. if the bullet can penetrate the cool wood block, the minimum velocity of the bullet is (3) m / s
20. The speed of a bullet hitting the board is 600 m / s, and it takes 0.001 s to get out of the board. The speed of a bullet passing through the board is 100 m / s The speed of a bullet hitting the board is 600 m / s, and it takes 0.001 s to get out of the board. The speed of a bullet passing through the board is 100 m / s. suppose that the bullet is decelerating and the mass of the bullet is 20 g. calculate the resistance of the bullet passing through the board and the thickness of the board