Monday, 20 January 2014

class 11 imp questions for final exam 2014


                                           Class 11 Physics
Important Questions for Finals.
Q1.Why is gravitational potential energy always negative?                            
Q2.Why mercury does not wet glass?                                                             
Q.3 Can a body have energy without momentum ?explain.                            
Q.4 What is the angle of friction between two surfaces in contact , if coefficient of friction is 1/√3.
Q.5 Equal masses of two substances of densities  p1 and p2 are mixed together .What is the density of the mixture.
Q6.A light body and a heavy body have same momentum , which one has greater KE?
Q.7 A uniform chain of length L and mass M is lying on a smooth table and one third of its length is hanging vertically down over the edge of the table. If g is acceleration due to gravity .calculate work required to pull the hanging part on the table.
Q.8 Find the angle through which a cyclist bends when he covers a circular path 34.3m long in √22 sec .Given g=9.8 m/s2.
Q.9 How far away from the surface of earth does the value of g is reduced to 4% of
its value on the surface of the earth Given radius of earth = 6400km
Q.10 If the Kinetic Energy of a body increases by 300%, by what % will the linear momentum of the body increase?
Q.11 A satellite is revolving is a circular path close to a planet of density P. find an
expression for its period of revolution?
Q.12 Which is more elastic rubber or steel? Explain.
Q.13 Explain Magnus Effect with its diagram.
Q.14 State and prove work energy theorem.
Q.15 Explain the principle of working of hydraulic brakes with its diagram.
Q.16 Derive the expression for the rise of liquid in a capillary tube ?
Q.17 Moon does not have atmosphere ,Why? Derive the relation for Escape velocity of a planet, does it depend upon the mass of satellite.
Q.18. Derive the expression for elastic potential energy in a stretched wire?
Q.19. Calculate the work done in splitting a drop of water of radius 1 cm to 106 droplets. Given surface Tension of water = 0.072 N/m.
Q.20. Describe the variation of acceleration due to gravity (g) with depth and draw a graph showing the variation of g as one moves outwards from the centre of earth.
Q.21.What is banking of tracks? Find an Expression for the velocity of a car moving along a banked track. what is optimum velocity?
Q.22 Derive expression for Bernoulli’s theorem?
 Q.23Derive the expression for the velocities of objects in elastic collision in one dimension.
Q.24 Write the number of significant figures in (a) 2.64 × 1024 kg  (b) 0.00786 g/cm3
Q.25 Can two streamline cross each other in flowing liquid ? Explain.
Q.26  In which motion linear momentum changes but K.E does not?
 Q.27What is the time period of simple pendulum at the centre of the earth?
Q.28 What is the S.I unit and dimensional formula for plancks constant?
Q.29 Why is difficult to stop bleeding from cut in human body at high altitudes?
Q.30 When air is blown between two balls suspended closed to each other. They are attracted towards each other. Why?
Q.31 What will be the effect on the duration of a day on earth, if the earth suddenly contracts?
Q.32  If the radius of the earth shrinks by 5%, mass remaining same , then how would the value of acceleration due to gravity change?
Q.33 Show that impulse of a force is equal to change in linear momentum produced by the force.
Q.34  why is it easier to pull than to push a body ?
Q.35  Write the dimension of aXb in the relation.
          F=ax + bt2, where F is force, x is distance and t is time.
Q.36. A particle is projected with velocity u making an angle with the horizontal direction. Write formula for:
(a) Time of Flight
(b) Horizontal Range
Q37. At what angle the horizontal range and the height for a projectile is equal ?
Q.38 Explain Hooke’s law with stress strain curve.
Q.39  Explain First law of thermodynamics with its equation.
Q.40 Explain  why hollow shaft is Stronger than solid shaft.
Q.41 A machine has a mass of 20kg. It fires 35gm bullets at the rate of 4 bullets per second , with the speed of 400 m sec-1.what force must be applied to the gun to keep it in position ?
Q.42. Define Cp and Cv and Derive the relation between them..
Q.43. Derive the equation by calculus method
           S = ut + ½ at2
     Where symbol has their usual meanings
Q.44 State and prove theorm of parallel axis.
Q.45.Prove by calculus method , that the change in kinetic energy is equal to workdone.
Q.46 Eight rain drops of radius 1mm. each falling down with the terminal velocity of 5 cm/s combine to form a bigger drop. Find the terminal velocity of bigger drop.
Q.47 What do you mean by bending of cyclist and derive the expression for the angle of bending.
Q.48.Show the motion of a liquid in a U-tube is simple harmonic, find an expression for its time period.
Q.49 Find the scalar product between vectors A=3i - 2j + 4k and B = 2i - 4j + 3k.
 Q.50. Write the formula for Kinetic energy, Potential energy and total energy of a body executing SHM. Prove that energy that energy is directly proportional to square of amplitude and frequency.
Q.51.Define  three coefficients of expansion  α, β and γ and derive relation between them..
Q.52 Explain the construction and various operations for an ideal carnot heat engine working between two temperatures and  define its efficiency .
Q.53How much heat energy is required to heat 1 kg of water at 20 C to 100 C?
Q.54.A water pipe entering a holes has a diameter of 2 cm and the speed of water is 0.1 m/s. Eventually, the pipe tappers the diameter of 1cm.Calculate the speed of water in the trap portion.
Q.55.(a)State and prove parallelogram law of vectors addition.b)The x – t graph for two bodies in motion is as shown. Which body has more velocity.
Q.56.Derive the expression for torque in terms of  the Cartesian coordinate system.
Q.57.State Newton’s second law of motion on its basis derived the relation between force and acceleration.
Q.58.explain keplers law of planetary motion.
Q.59 Two bodies A and B having masses 5 kg and 6 kg respectively, have there equal momentum. Find ratio of  their Kinetic energies.
Q.60 Air is pushed into a soap bubble of radius r to double its radius , if the surface tension of the soap solution is S ,find the workdone.
Q.61 The resistance R=V/I, where V =100 ± 5 V and I =10 ± 0.2 A.Find the % error in R.
 Q.62 Suraj went to Big Bazaar to purchase certain goods .There he has noticed an old lady struggling with her shopping. Immediately he showed her the lift and explained to her how it carries the load from one floor to the next. Even then the Old lady was not convinced.. Then suraj took her in the lift and showed her how to operate it.. That old lady was very happy. (a)What values does Suraj possess? (b)An elevator can carry a maximum load of 1800 kg is moving up with a constant speed of 2 m/s , The frictional force opposing the motion is 4000 N. Determine the minimum power delivered by the motor to the elevator in watts as well as in horse power.(Value Based Question)
Q.63 Rakesh with the intention to win in the interschool sports practiced high jump every day for about a month. He participated and won I position in the interschool sports. (a) Comment upon the values Rakesh possesses. (b) Why does an athlete run some steps before taking a jump? (Value Based Question)
Q.64 Newton’s Second  law of motion is the real law of motion , Explain.
Q.65 Draw a graph showing static , limiting and kinetic friction ?
Q.66 . Having seen a big stone falling from the top of a tower Ravi pulled his friend Kiran away. The stone hit Ravi slightly and he got hurt. But he was saved from a major accident. (a)What made Ravi act in such a way. (b)From the top of a tower 100 m in height, a ball is dropped and at the same time another ball is projected vertically upwards from the ground with a velocity of 25 m/s.Find when and where the two balls meet. Take g = 9.8 m/sec2.(Value Based Question)
Q.67 A monkey is sitting on a tree. Rahim seeing the Monkey brought some fruits
and gave them to the Monkey, and ran into the house immediately. On hearing the
sound produced when Rahim was running the monkey was scared and climbed the
nearby tree. (a) What values of Rahim inspired you?
(b)A monkey of mass 40 Kg climbs on a rope which can stand a maximum tension of 600 N .
In which of the following cases will the rope will break. The monkey
(I) Climbs up with an acceleration of 6 m/s2
(II) Climbs down with an acceleration of 4 m/s2
(III) Climbs up with a uniform speed of 5 m/s
(IV) Falls down the rope nearly under gravity?
(Take g= 10 m/s2) (Ignore the mass of the rope) (Value Based Question)
Q.68 A sports teacher was training the children for march-past. On their way they
come across a bridge .Then the physical education teacher stopped the children from
marching on the bridge.
 (a) Comment upon the values of sports teacher.
b) Also explain what is meant by Resonance.
Q.69 (a)Ravi has to attend to an interview . He was not well. He took the help of his friend Raghavan. On the way office Ravi felt giddy, He vomited on his dress. Raghavan washed his shirt. He made Ravi to drink enough amount of water. In spite of doing ,a foul smell was coming from the shirt. Then Raghavan purchased a scent bottle from the nearby cosmetics shop and applied on Ravi. Ravi attended the interview, Performed well .Finally he was selected.
(a)What values do you find in Raghavan?
(b)The velocity of air molecules is nearly 500m/s. But the smell of scent spreads very slowly, Why? (Value Based Question)
Q.70 Ratan noticed that his grandfather to be suffering from fever. He took him to the doctor The
doctor gave him some pills .When the pills were used he sweated much, after some time became
normal.Rahim enquired the Doctor about how his grandfather became normal .
(a)According to you what values are possessed by Ratan?
(b) A child running a temperature of 101°Fis given an Antipyria which causes an increase in the rate of evaporation of the body. If the fever is brought down to 98°F in 20 mts, what is the amount of heat lost by the body? . The mass of the child is 30 kg. (Value Based Question)
Q.71 (a) Savita was surprised to see oil spreading on to the surface of water and asked her mother to explain why oil spreads on to the surface of water. Her mother explained her daughter the reason behind it. By going through the explanation she thought of learning more about the other scientific phenomenon also. What qualities do you can find in Savita?
(b) Oil spreads over the surface of water whereas water does not spread over the surface of oil. Why? (Value Based Question)
Q.72(a) A small hair piece has fallen into the eye of Suresh. It caused itching sensation in the eye of Suresh seeing that Hari, who is a friend of Suresh, took him to the eye specialist. The Doctor removed it. Suresh expressed his gratitude to Hari.Comment upon the values of Hari.
(b) A student measure the thickness of a human hair by looking at it through a microscope of
magnification 100.He makes 20 observations and finds that the average width of the hair in the field of view of the microscope is 3.5mm. What is the estimate on the thickness of hair?
Q.73 Vineet saw his uncle planting seeds in the land. His uncle does not know methods of growing plants. Then he decided to make his uncle aware of this. He explained the importance of ploughing the land before planting the seeds. Uncle is convinced with his ideas. He planted accordingly. The plants grown successfully.
(a) What can you say about Vineet?
(b) What is the utility of ploughing a field? Does it help the soil to retain moisture
(Value Based Question)
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Sunday, 19 January 2014

MCQ of Work And Energy


MCQ Of Work And Energy
1. When a body falls freely towards the earth, then its total energy
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases
2. A car is accelerated on a levelled road and attains a velocity 4 times of its initial velocity. In this process the potential energy of the car
(a) does not change
(b) becomes twice to that of initial
(c) becomes 4 times that of initial
(d) becomes 16 times that of initial
3. In case of negative work the angle(in degree) between the force and displacement is
(a) 0 (b) 45 (c) 90 (d ) 180
4. An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same
(a) acceleration
(b) momentum
(c) potential energy
(d) kinetic energy
5. A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be (g =10 m s–2)
(a) 6 ×103 J
(b) 6 J
(c) 0.6 J
(d) zero
6. Which one of the following is not the unit of energy?
(a) joule
(b) newton metre
(c) kilowatt
(d) kilowatt hour
7. The work done on an object does not depend upon the
(a) displacement
(b) force applied
(c) angle between force and displacement
(d) initial velocity of the object
8. Water stored in a dam possesses
(a) no energy
(b) electrical energy
(c) kinetic energy
(d) potential energy
9. A body is falling from a height h. After it has fallen a height h/2 , it will possess
(a) only potential energy
(b) only kinetic energy
(c) half potential and half kinetic energy
(d) more kinetic and less potential energy
10. How are Joule (J) and ergs (erg) related?
(a) 1J = 107 erg (b) 1erg = 10 -7J (c) 1J = 10-7 erg (d) None

Floatation imp Question class IX


"Om Sai Ram"
Floatation
1. Give reason why, a block of plastic when released under water comes up to the surface of water.
Ans: It is because of buoyancy force
2. Define density. What is the SI unit of density?
Ans: Mass per unit volume of a substance is called density.
The SI unit of density is kg/m3 or gm/cm3
3. Name and define SI unit of pressure.
Ans: Pascal or Newton/square meter
1 Pascal is the pressure act when 1 N  force acts perpendicular on unit area.
4. What do you understand by the term buoyancy?
Ans: Tendency of fluid to exert an upward force when a body is immersed in to it is called buoyancy
5. Why does a mug full of water feel lighter inside water?
Ans: a mug full of water feels lighter inside water because of buoyancy force
6. A perpendicular force of 50 N acting on a surface generates a pressure of 250 Pa. Calculate the area of cross-section of the surface on which pressure is acting.
Ans: p = F/A Þ A = F/p Þ 50 N/250 Pa = 0.2 m2
7. What is a lactometer used for?
Ans: lactometer used for finding purity of milk
8. State the unit of density and relative density in SI system.
Ans: The unit of density is  kg/m3
There is no unit of relative as it is ratio of same physical quantity.  
9. State Archimedes’ principle.
Ans: When a body is immersed partially or completely in a fluid (liquid or gas), it experiences an up thrust or buoyant force which is equal to the weight of the fluid displaced by the body.
10. What is meant by buoyant force?
Ans:  if a body is immersed partially or completely in a fluid, it experiences an up thrust called buoyant force.
11. A cork floats while the nail sinks in water. Give reason.
Ans: Weight of cork is  less than buoyant force acting on it so it floats Where as : Weight of the nail  is  more than buoyant force acting on it so it sink
12. What is the principle of floatation?
Ans: A body floats is a liquid if weight of the liquid displaced by the immersed portion of the body is equal to the weight of the body.
13. A body of mass 400 g has a volume of 300 cm3. Will body sink in water or not? [Density of water = 1000 kgm–3]
Ans:  density of body =m/v= 400/300=1.3gm/cm3 which is greater than density of water 1gm/cm3 Hence, Body will  sink in water.
14. When we stand on loose sand, our feet go deep into the sand. But when we lie down on the sand our body does not go that deep in the sand. Why?
Ans: when we lie down on the sand our body exert same force on large are that reduce pressure and our body does not go that deep in the sand.
15. Why is it easy to walk on sand with flat shoes, then with high heel shoes?
Ans: flat shoes exert force on large surface area and less force act on sand this make easy to walk on sand.