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Download the collection of questions asked in previous CBSE board exams from the chapter Wave Optics.
Practising the previously asked questions is a good idea to prepare for the exams.
It has been a long time since I have been in a physics class. My question should, I believe, be relatively simple. We are developing a prototype using a spool, cable, and pulleys to lift a weight. I would like to know the mechanical advantage presented in the design I am attaching as well as any explanations you might have in how the determination was arrived at. I am thinking it presents a 6:1 or 7:1 lifting advantage, but I may be way off. Please feel free to disabuse any assumptions I may have on this.
Doug Rasmussen asked
“A particle of mass 2m is on a plane inclined at an angle 36.86 to the horizontal. The particle is attached to one end of a light inextensible string. The string runs parallel to a line of greatest slope of the plane, passes over a smooth pulley at the top of the plane and then hangs vertically carrying a particle of mass 3m at its other end. The system is released from rest with a single taut. Find the acceleration of each particle and tension in the string when the particles are moving freely, given that the plane is smooth.”
When I interacted with students of class 11 and 12, I came to know that Physics is one of the subjects they FEAR most during exam time. Though it seems difficult to score high marks, it is not actually so. Here are some suggestions you can easily follow to score more in Physics without much strain.
“Nobody plans to fail, but plans to fail”
Yes, A well planned study habit is essential to score more.
If you analyse the pattern of exam in class XI and XII (CBSE) the most of the marks are distributed among 3 marks questions and 5 marks questions which emphasizes the knowledge of concepts. SO, if you find it difficult to pass, then the following plan of action will easily work out.
- Identify all portions from which 5 marks questions can be asked and practice them well.
- Identify all portions from which three marks questions can be asked and practice them well.
- Learn all Laws, definitions, principles
- Practice all diagrams.
- Practice all solved problems given in text
These links may be helpful
Just try this routine and see whether you are scoring more or not.
For those already got pass marks can also try the above to better plus
- Solve all exercises and additional exercises from NCERT Textbook.
- Get a collection of all one marks questions and Two marks questions preferably from previous ten years’ question papers and find answers to them.
Those who want to excel further and look forward to entrance examinations, IIT, MBBS etc the following links to books will help.
Numericals from Newton’s Laws of motion based on F=ma (For calss XI students of Kendriya Vidyalaya Pattom)
Download the questions and solve them and submit on or before 9 Oct 2014
- A force acts for 10 s on a body of mass 10 kg after which the force ceases and the body describes 50 m in the next 5 s. Find the magnitude of the force. [Ans: 10 N]
- A truck starts from rest and rolls down a hill with constant acceleration. It travels a distance od 400 m in 20s. Calculate the acceleration and the force acting on it if its mass is 7 metric tonnes. [Ans: 2 m/s2, 14000N]
- A motor car running aat the rate of 7 m/s can be stopped by applying brakes in 10 m. Show that total resistance to the motion, when the brakes are on is one fourth of the weight of the car.
- In an Xray machine, an electron is subjected top a force of 10-23 N. In how much time the electron will cover a distance of 0.1 m,? Take the mass of the electron = 10-30 kg
If the definition of the speed of light is for massless particles, then how is a proton, having mass, accelerated to the speed of light? This sounds like a conumdrum.
No massive particle has not so far crossed the speed of light. Even the extremely light particles – the neutrinos – couldnot cross the speed of light. Protons have not crossed the speed of light. When it nears the speed of light, the relativistic mechanics will become prominent and the it is to be treated is different from the classical mechanics.
1. In first case we have the box with weight, say, 10 Newtons on incline. We calculate two components (perpendicular and parallel)of weight. We calculate normal force and force of friction. The box is at rest.
2. In second case we have ball on incline, made of same material as box from first case. Weight of the ball is the same as in first case, components of weight are the same as in first case. Normal force and friction have the same amount as in the case of box. But,unlike the box, ball is moving – it slides down. How’s that possible? If calculated net force is zero?
It is not true that the ball slides, but it will roll down.
In the first case, the forces balance each other and there is no motion.
In the second force, the frictional force acting tangentially backwards (up the incline) and the component of weight of the ball acting parallel to the plane and through the centre of the ball constitute a couple and tends to rotate it. Now there is no sliding; it rolls.
(If any further clarification is required please post as comment to this post)
Please refer to http://www.real-world-physics-problems.com/rolling-without-slipping.html for detailed treatment of the Physics of rolling without friction.