Q1. A turntable must spin at 33.3 rpm (3.49 rad/s) to play an old-fashioned vinyl record. How much torque must the motor deliver if the turntable is to reach its final angular speed in 2.0 revolutions, starting from rest? The turntable is a uniform disk of diameter 30.5 cm and mass 0.22 kg. Answers; 0.0012 N m

Q2. Four masses are arranged as shown. They are connected by rigid, mass less rods of lengths .75 m and .50 m. What torque must be applied to cause an angular acceleration of 0.75 rad/s squared about the axis shown? Answers ; 1.5 N m
masses are 4kg,5kg,3kg,2kg axis is parallel to 0.5 m rod.

Q3. A bucket of water with a mass of 2.0 kg is attached to a rope that is wound around a cylinder. The cylinder has a mass of 3.0 kg and is mounted horizontally on the frictionless bearing. The bucket is released from rest. a) find its speed after is has fallen through a distance of .80 m. What are b) the tension in the rope and c) the acceleration of the bucket?
Answers ; a) 3.0 m/s b) 8.4 N c) 5.6 m/s squared
Q4. A block moves at 5m/s in the positive x direction and hits an identical block, initially at rest. A small amount of gunpowder had been placed on one of the blocks. The explosion does not harm the blocks but it doubles their total kinetic energy. After the explosion the blocks move along the x axis and the incident block has a speed in m/s of:

Q5. A spoked wheel with a radius of 40.0 cm and a mass of 2.00 kg is mounted horizontally on frictionless bearings. JiaJun puts his .500 kg guinea pig on the outer edge of the wheel. The guinea pig begins to run along the edge of the wheel with a speed of 20.0 cm/s with respect to the ground. What is the angular velocity of the wheel? Assume the spokes of the wheel have negligible mass. Answers; 0.125 rad/s

Q6. A painter (mass 61 kg) is walking along a trestle, consisting of uniform plank (mass 20.0 kg, length 6.00 m) balanced on two sawhorses. Each sawhorse is placed 1.40 m from an end of the plank. A paint bucket (mass 4.0 kg, diameter 28 cm) is placed as close as possible to the right-hand edge of the plank while still having the whole bucket in contact with the plank. a) How close to the right hand edge of the plank can the painter walk before tipping the plank and spilling the paint? b) How close to the left hand edge can the same painter walk before causing the plank to tip? (Hint; as the painter walks towards the right hand edge of the plank and the plank starts to tip clockwise, what is the force acting upward on the plank from the left hand sawhorse support) Answers; a)0.96 from RH edge b) 0.58 m form LH edge

Q7. A bicycle has wheels of radius 0.28 m. Each wheel has a rotational inertia of 0.075 kg·m2 about its axle. The total mass of the bicycle including the wheels and the rider is 74 kg. When coasting at constant speed, what fraction of the total kinetic energy of the bicycle (including rider) is the rotational kinetic energy of the wheels?

Q8. Two ice skaters of = mass grab hands and spin in a circle once very four seconds. Their arms are each 0.76m long, and they each have a mass of 55.0 kg. How hard are they pulling on one another?

ONLINE TESTING PLATFORM

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The link for the same is www.sbtopperpoint.vriti.com .

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Just have a look. It may suit your requirement.

CENTUM 2010

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CBSE 2009 Result

What a performance !!

Out of 10 students, 8 student has scored 95 in Physics and other 2 80 marks.

In Maths Highest is 99.Same 8 Students has scored between 90 -99. Other Two students 80 Marks.

Fly with us!!!!

Week No. 3 : AIEEE Special

For any examination, if you wish to get success then can you tell me what is most important? Mail me at sbtopperpoint@gmail.com

This is very important because if you get solution to this question, I can assure you 50% of your preparation is over.

ONLINE ASSISTANCE FOR CBSE/AIEEE/IIT JEE

Dear friendz

On your advice and demand, we have decided to start online assistance for both mathematics and physics.

Classes will be regularly held from 10.00 pm -11.00 pm.

For this you have to open a skype account. and you have to add my id.

SKYPE ID dr.s.kumar

You can refer your friends / relatives.

The fee is only Rs. 1,500 / subject/ month. For easy access, i have decided to keep timeframe from 1st of each month.

Hope this will benefit everybody.

The details of timings are:
CBSE XII Physics Monday/Wednesday 10.00-11.00pm
CBSE XII Mathematics Tuesday/Thursday 10.00-11.00 pm
CBSE XI Mathematics Saturday 9.00-10.00 pm
CBSE XI Physics Saturday 10.00-11.00pm
CBSE X Mathematics Friday/Sunday 9.00-10.00pm

For any other terms and conditions, mail me sbtopperpoint@gmail.com

Test your Mathematics

Q1. You roll two dice. The first die shows a ONE and the other die rolls under the table and you cannot see it. Now, what is the probability that both die show ONE?

Q2. Suppose that an asteroid orbits the sun (in an elliptical orbit). And suppose that the longest opposite ends of the orbit are 800 million miles apart and that the shortest opposite ends are 200 million miles apart. Give an equation for the orbit of the asteroid.

Q3. A teacher is making a multiple choice quiz. She wants to give each student the same questions, but have each student's questions appear in a different order. If there are twenty-seven students in the class, what is the least number of questions the quiz must contain?

Q4. In a triangle , Anle B =80º,angle C = 34º and a = 16.Find the length of b to the nearest tenth.

Q5. The sum of the interior angles of a triangle is 180º, of a quadrilateral is 360º and of a pentagon is 540º. Assuming this pattern continues, find the sum of the interior angles of a dodecagon (12 sides).

Q6.let R and S in the figure be defined as follows: R is the region bound in the 1st and 2nd quadrants bounded by the graphs of y=3-x*2 and y=2*x. S is the shaded region in the first quadrant bounded by the two graphs, the x-axis and y-axis b) find the volume of the solid generated when R is rotated about the horizontal line y= -1.

Analysis and solution for Members only.

TEST SERIES 1: PHYSICS

Q.1 A stone falls freely from rest. The total distance covered by it in the last second of its motion equals the distance covered by it in the first three seconds. How long does the stone remain in air?
(a) 10 sec
(b) 5 sec
(c) 15 sec
(d) cannot be determined
Q2. A cricketer can throw a ball to a maximum horizontal distance of 100 m.With the same effort he throws the ball vertically upwards. What is the maximum height attained by the ball?
(a) 100 m
(b) 150 m
(c) 50 m
(d) 200 m
Q3 A body is projected with kinetic energy K at an angle of 60ْwith the horizontal. What is its potential energy at the highest point of its trajectory?
(a) 4K/3
(b) K
(c) 2k
(d) 3K/4
Q4. A man runs at a speed of 4kmph for the first half of the distance and runs at 5kmph for the remaining part of the journey. What is his average speed over the entire journey ?
(a) 4.5 kmph
(b) 40/9 kmph
(c) 20/9 kmph
(d) 5.4 kmph
Q5. A car moves at a speed of 36 kmph on a level road. The coefficient of friction between the tyres and the road is 0.8. The car negotiates a curve of radius R.What is the minimum value of R for which the car just starts skidding?
(a) 10 m
(b) 12.5 m
(c) 25 m
(d) 0.08 m
Q6. A stone tied to the end of a string 75.0 cm long is whirled in a horizontal circle with a constant speed. If the stone makes 20 revolutions in 25 seconds, find (i) the speed of the stone along the circle and (ii) acceleration of the stone.
(a) 3.77 m/s, 18.93 m/s^2
(b) 5.028 m/s, 33.7077 m/s^2
(c) 3.77 m/s, 0 m/s^2
(d) 14 m/s, 0 m/s^2
Q7. The distance x moved by a body of mass 0.5 Kg by a force varies with time as x = 3*t^2 + 4t +5 where x is expressed in metre and t in second. What is the work done by the force in the first 2 seconds? t^2 = t*t, i.e., t squared
(a) 60 J
(b) 75 J
(c) 64 J
(d) 3 J
Q8. A wire of cross-sectional area A at temperature T is held taut with negligible tension between two rigid supports. If the wire is cooled to a temperature (T – t), what is the tension developed in the wire? The coefficient of linear expansion is 'a' and the Young’s modulus of the wire is Y.
(a) YAat
(b) Yt
(c) AY
(d) Cant be determined
Q9 A copper block of mass 2 Kg is heated to a temperature of 500ْC and then placed in a large block of ice at 0ْC. What is the maximum amount of ice that can melt? The specific heat of copper is 400 J/kg/c and the latent heat of fusion of ice is 3.5 × 10^5 J/kg
(a) 7/8 kg
(b) 8/7 kg
(c) 8 kg
(d) 7 kg
Q10 When 20 J of work is done on a gas, 40 J of heat energy is released. If the initial internal energy of the gas was 70 J, what is the final internal energy?
(a) 50 J
(b) 100 J
(c) 25 J
(d) 200 J
Q11. Cooking vegetables and other food in a pressure cooker saves time and fuel because
(a) under increased pressure, water can be made to boil at a temperature much lower than 100 C
(b) heat losses are reduced to a minimum
(c) condensation of steam is prevented
(d) under increased pressure, water can be made to boil at a temperature much higher than 100ْC
Q12. Which of the following statements is true about a gas undergoing an adiabatic change?
(a) the pressure of the gas remains constant
(b) the volume of the gas remains constant
(c) the gas is completely insulated from the surroundings.
(d) the temperature of the gas remains constant
Q13 Two positive point charges, 12 microColoumb and 8 microCouloumb respectively, are placed 10 cm apart in air. What is the work done in bringing them 4 cm closer? Use 1/4*pi*e = 9*10^9
(a) 3.4 J
(b) 154 J
(c) 384 J
(d) 5.8 J
Q14. Two point charges +4q and +q are placed 30 cm apart. At what point on the line joining them will the electric field be zero?
(a) At the mid-point
(b) At no point
(c) 20 cm from +q
(d) 20cm from +4q
Q15. The refractive index of a medium is 1.732 . Calculate the angle of refraction if the unpolarized light is incident on it at the polarizing angle of the medium (in degrees)
(a) 30 degrees
(b) 60 degrees
(c) 90 degrees
(d) It reflects
Q16. A cell supplies a current of 0.9 A through a 2 Ohm resistor and 0.3 A through a 7 Ohm resistor. What is the internal resistance of the cell
(a) 2 ohm
(b) 14/9 ohm
(c) 0.5 ohm
(d) 9 ohm
Q17. A capacitor is charged using a battery. Then the battery is disconnected. Now a dielectric slab is introduced between the plates which results in the
(a) decrease in the potential difference between the plates and reduction in the stored energy but no change in the charge on the plates
(b) reduction of charge on the plates and increase of potential difference between the plates
(c) increase in the potential difference between the plates and reduction in the stored energy, but no change in the charge of the plates
(d) None of these
Q18. When a capacitor is connected to a battery
(a) no current flows in the circuit at all
(b) a current flows in the circuit for some time and then decreases to zero
(c) the current keeps on increasing, reaching a maximum value when the capacitor is charged to the voltage of the battery
(d) an alternating current flows in the circuit
Q19. An electric dipole placed with its axis inclined at an angle to the direction of a uniform electric field experiences
(a) neither a force nor a torque
(b) a force as well as a torque
(c) a force but no torque
(d) a torque but no force
Q20. Which of the following is true in the case of inelastic collisions with respect to Total Energy, Kinetic Energy and Momentum respectively
(a) Not Conserved, Not Conserved, Conserved
(b) Conserved, Conserved, Not Conserved
(c) Conserved, Conserved, Conserved
(d) Conserved, Not Conserved, Conserved

Analysis and discussions will be with members only.

Useful Article : Relation and Function 1

Relations
A Relation is a rule that gives one or more outputs for every valid input. The input is the Independent Variable, and x is often used as the input variable. The output is the dependent variable, and y is often used as the output variable. The output depends on the input value.

The relation may be described as:

1. Set of ordered pairs: The {} represents the set, and (,) represents the ordered pair. The ordered pair means (1, 2) and (2, 1) are different. The first element in the ordered pair is the input, and the second element is the output.Example: { (-2, 1), (0, 3), (2, 1), (-1, 5) }
2. An equation: An equation that relates the input and output. Examples: y=x2+2x=-1 x2+y2=25
3. A Rule/ description in words: A rule that relates the input and the output. Examples: The output is three times the input; the width of the rectangle is 5 units more than the length.
4. An arrow diagram:
5. A continuous graph:
6. A scatter plot: It is also known as a discrete graph.
7. An input/output diagram
8. A table:

Week No. 2: AIEEE Special

Q1. The only force acting on a 2.0 kg body as it moves along the positive x axis has an component of force -6x N, where x is in meters. The velocity of the body at x=3.0 m is 8.0 m/s. (a) What is the velocity of body at x=4.0 m ? (b) At what positive value of x will the body have a velocity of 5.0m/s ?

Q2. A 0.30 kg mass sliding on a horizontal frictionless surface is attached to one end of a horizontal spring (with k=500 N/m) whose other end is fixed. The mass has a kinetic energy of 10J as it passes through its equilibrium position. (a) At what rate is the spring doing work on the mass as the mass passes through its equilibrium position. (b) At what rate is the spring doing work on the mass when the spring is compressed 0.10 m and the mass is moving away from the equilibrium position ?

Week No.1 : AIEEE Special

Q1. Two electrons are fixed 2.0 cm apart. Another electron is shot from infinity and comes to rest midway between the two. What was its initial speed ?
Q2. A particle of positive charge Q is fixed at point P. A second particle of mass m and negative charge -q moves at a constant speed in a circle of radius r1, centered at P.. What is the work done by an external agency to increase the radius to r2?

TARGET AIEEE 2010

In this section we will give tips for success in Physics & Mathematics for above examination. Just visit regularly..

TARGET CBSE 2010

In this section we will give tips for scoring >90% in Physics & Mathematics. For more tune into this website.

For sample class it is only Rs. 150/- class subject to maximum 3 classes.

Terms and Conditions

1. For sample class fee is payble either advance / at the end of class.

2. First 2 month fee is payble in advance.

Welcome

Welcome to Dr. SB's Topper Point.

Here it is our constant endeavour to improve the teaching methodology enabling students better confidence and success.

We have listed below our idea of accepting students.

Mode of Teaching : Home Tution

Class undertaken : X , XII CBSE MATH / PHYSICS
( Students aspiring for AIEEE will get maximum benefit)

Fee Details : Monthly fees Rs. 3000/-