4. C.O.M.E and Apps Class lecture for Yakeen.pptx

Class lecture for Yakeen

1. Prashanth Mateti Subject Name - PHYSICS Lecture No. 4 BATCH CODE – 66-PJ452MA Chapter Name – Work, Energy and Power

2. Conservative Forces and C.O.M.E Subtopic Today's Goal

3. Question Potential to kinetic and to heat energy Kinetic to potential and to heat energy Chemical to heat and to potential energy Kinetic to heat and to chemical energy A B C D A cyclist free-wheels from the top of a hill, gathers speed going down the hill, applies his brakes and eventually comes to rest at the bottom of the hill. Which one of the following energy changes take place.

4. Question A rocket starts on the ground at rest. Its final speed is 500 m/s and height is 5000 m. If the mass of the rocket stays approximately 200 kg. Find the work done by the rocket engine.

5. A block slides down the inclined k m x i d θ   h C B A x

6. Question A 1500-kg car’s brakes failed and it coasts down a hill from rest. The hill is 10 m high and the car has a speed of 12 m/s at the bottom of the hill. How much work did friction do on the car?

7. Question Two blocks are connected by a light string that passes over a frictionless pulley. The block of mass m 1 lies on a horizontal surface and is connected to a spring of force constant k. The system is released from rest when the spring is unstretched. If the hanging block of mass m 2 falls a distance h before coming to rest, calculate the coefficient of kinetic friction between the block of mass m 1 and the surface. k m 1 m 2 h

8. Question One end of a spring of natural length h and spring constant k is fixed at the ground and the other is fitted with a smooth ring of mass m which is allowed to slide on a horizontal rod fixed at a height h. Initially, the spring makes an angle of 37° with the vertical when the system is released from rest. Find the speed of the ring when the spring becomes vertical. [HCV]

9. Question A small block of mass 100 g is pressed against a horizontal spring fixed at one end to compress the spring through 5.0 cm. The spring constant is 100 N/m. When released, the block moves horizontally till it leaves the spring. Where will it the hit the ground 2 m below the spring? [HCV]

10. Question Figure shows a spring fixed at the bottom end of an incline of inclination 37°. A small block of mass 2 kg starts slipping down the incline from a point 4.8 m away from the spring. The block compresses the spring by 20 cm, stops momentarily and then rebounds through a distance of 1 m up the incline. Find (a) the friction coefficient between the plane and the block and (b) the spring constant of the spring. Take g = 10 m/s 2 [HCV]

11. Question   [IE IRODOV]

12. Question A small heavy block is attached to the lower end of a light rod of length l which can be rotated about its clamper upper end. What minimum horizontal velocity should the block be given so that it moves in a complete vertical circle? [HCV]

13. Question Consider the situation shown in figure. Initially the spring is unstretched when the system is released from rest. Assuming no friction in the pulley, find the maximum elongation of the spring. [HCV]

14. Question   [HCV]

15. Question A block of mass 0.18 kg is attached to a spring of force constant 2 N/m. The coefficient of friction between the block and the floor is 0.1. Initially the block is at rest and the spring is unstretched. An impulse is given to the block as shown in the figure. The block slides a distance of 0.06 m and comes to rest for the first time. The initial velocity of the block in m/s is v = N/10. Then N is [JEE 2011]

16. Question Two blocks A and B are connected to each other by a string and a spring; the string passes over a frictionless pulley as shown in the figure. Block B slides over the horizontal top surface of a stationary block C and the block A slides along the vertical side of C, both with the same uniform speed. The coefficient of friction between the surfaces of blocks is 0.2. Force constant of the spring is 1960 N/m. If mass of block A is 2 kg. Calculate the mass of block B and the energy stored in the spring. [JEE 1982]

17. Question A string, with one end fixed on a rigid wall, passing over a fixed frictionless pulley at a distance of 2 m from the wall, has a point mass M = 2 kg attached to it at a distance of 1 m from the wall. A man m = 0.5 kg attached at the free end is held at rest so that the string is horizontal between the wall and the pulley and vertical beyond the pulley. What will be the speed with which the mass M will hit the wall when the mass m is released? (Take g = 9.8 m/s 2 )

18. Question Consider the situation shown in figure. The system is released from rest and the block of mass 1.0 kg is found to have a speed 0.3 m/s after it has descended through a distance of 1 m. Find the coefficient of kinetic friction between the block and the table. [HCV]

19. Question   [IE IRODOV]

20. Work Done and Power Q. A B C D

21. Work Done and Power Q. A B C D

22. Work Done and Power Q. A B C D

23. Work Done and Power Q. A B C D

24. Work Done and Power Q. A B C D

25. Work Done and Power Q. A B C D

26. Work Done and Power Q. A B C D

27. Work Done and Power Q. A B C D

28. Work Done and Power Q. A B C D

29. Work Done and Power Q.

30. Work Done and Power Q.

31. Problems with Friction Q.

32. W ork, Energy and Power Power Chap Name Next Lecture's Goal 1. Sub Top

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