![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
Under the action of horizontal constant force, the object starts to move from rest on the horizontal plane. When the displacement is s, f is removed, and the object continues to move forward for 3S, and then stops moving. If the road condition is the same, the friction force and the maximum kinetic energy of the object are () A. f=F3B. f=F4C. EK=2Fs3D. EK=3Fs4
A. B. in the whole movement process of the object, from the kinetic energy theorem: fs-f (s + 3S) = 0-0, the solution: F = F4; so a is wrong, B is correct; C, D, from the beginning of the movement of the object to the withdrawal of the external force, from the kinetic energy theorem: FS FS = ek-0, the solution: EK = 3fs4; so C is wrong, D is correct
RELATED INFORMATIONS
- 1. An object with mass m = 10kg is still on the horizontal plane and starts to move under the action of horizontal constant force F = 20n The acceleration of gravity g = 10m / S2 (1) if the horizontal plane is smooth, calculate the acceleration A1 and the velocity at the end of 2 seconds (2) if the horizontal plane is rough and the dynamic friction coefficient between the object and the horizontal plane is 0.1, calculate the acceleration A2
- 2. The stiffness coefficient of the spring is k = 20n / cm, with which a 20kg object is pulled to move on the horizontal plane. When the elongation of the spring is 4cm, the object just moves in a uniform straight line on the horizontal plane, and the speed is 4m / s. when the elongation of the spring is 6cm, the speed of the object moves for 2S, and then the distance that the pulling object can continue to slide is removed
- 3. A light spring with stiffness coefficient of 200N / m, the original length is 20cm, when its deformation is 10cm, the spring state and elastic force are () A. The spring must be in tension. B. the spring may be in compression. C. the spring force is 40nd. 20n
- 4. How much tension is used to lengthen a spring with a stiffness coefficient of 200N / m from 50cm to 70cm?
- 5. How much work is done to pull a spring from 10 cm to 13 cm, the stiffness coefficient is 200 N / m
- 6. A rectangular board, can you cut this board into two pieces, and then put it together into a square desktop? Please draw a picture to show your spelling. The side length of the square How much is it? It's 18 decimeters long and 8 decimeters wide
- 7. How many planks does it take to make the smallest square with a rectangle 12cm long and 8cm wide?
- 8. How many pieces do you need to make the smallest square with a kind of rectangular board 20cm long and 12cm wide?
- 9. When t = 0, x = 12cm, the direction is positive. How long does it take to return to the equilibrium position?
- 10. Uncle Li uses 24cm long, 12cm wide and 6cm thick bricks to build a 1.8m long, 24cm wide and 9dm high rectangular brick wall in the yard. How many bricks are used for this wall
- 11. There is a piece of wood on the horizontal ground with mass m, and the coefficient of sliding friction between it and the ground is μ. Under the action of the horizontal constant force F, the object starts to move from rest. After time t, the force F is removed, and the object moves forward for time 2T before it stops______ ．
- 12. What is the instantaneous power of an object resting on a smooth horizontal plane with a mass of M and subjected to a constant horizontal force F. for T seconds
- 13. The mass m of an object resting on a smooth horizontal surface is acted by a horizontal constant force F, and the instantaneous power is obtained in T seconds
- 14. A piece of wood with mass m is still on a smooth horizontal plane. Starting from t = 0, a horizontal constant force of F is applied to the piece. At t = t, the power of F is () A. F2T2mB. F2T mC. F2T 2mD. F2T22m
- 15. A block of wood with mass m is still on a smooth horizontal plane. Starting from t = 0, a horizontal constant force with size f is applied on the block. After t0 time, F A block of wood with mass m is still on a smooth horizontal plane. Starting from t = 0, a horizontal constant force with size f is applied on the block. The work w done by F in t0 and the power R of F at t0 are calculated
- 16. A wooden block with mass m is still on a smooth horizontal ground. Starting from t = 0, a horizontal constant force with size f is applied on the wooden block. At t = T1, the power of force F is the answer. How to calculate f ^ 2 / m * t?
- 17. A block of wood with mass m is still on the horizontal ground. Starting from t = 0, a horizontal constant force with size f acts on the block. At t = T1, the force F decreases What is the power? Why is it uniform acceleration?
- 18. An object with a mass of 2kg is still on a horizontal plane and starts to move under the action of a horizontal constant force of 10N. It moves 8m in 2S 1. Work done by horizontal constant force W 2. Average power of work done by horizontal constant force P The instantaneous power p'of the work done by the horizontal constant force at the end of 3.2 seconds How can FV get 400. Wrong,
- 19. On a smooth horizontal table, there is an object with a mass of 2kg. It receives two forces at an angle of 60. In the horizontal direction. The two forces are 14N. Find the acceleration of the object
- 20. There is an object on the horizontal table with a mass of 2kg. It is subjected to two forces in the horizontal direction at 90 degrees to each other, both of which are 14N. What is the acceleration of the object and in what direction