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MathsMediumMCQ2021 · 26 Aug Shift 2

Q67. x→2(∑9 (1) 5 (2) 7 24 36 (3) 1 (4) 9 5 44

What This Question Tests

This question tests the ability to calculate the sum of a finite series involving 'n' and then evaluate a limit by direct substitution, assuming the given summation index and expression.

Concepts Tested

Summation of seriesLimits of polynomial expressions

Formulas Used

Summation formulas: Σn = n(n+1)/2, Σn² = n(n+1)(2n+1)/6

Direct substitution for limits

📚 NCERT Sections This Tests

1.3Define The Following Terms:

Chemistry Class 11 · Chapter 1

69% match

1.3 Define the following terms: (i) Mole fraction (ii) Molality (iii) Molarity (iv) Mass percentage.

8.17Complete Each Synthesis By Giving Missing Starting Material, Reagent Or Products

Chemistry Class 12 · Chapter 8

68% match

8.17 Complete each synthesis by giving missing starting material, reagent or products

5.2Lists The Kinetic Energies For Various X I

Physics Class 11 · Chapter 5

68% match

5.2 lists the kinetic energies for various x i objects. where the summation is from the initial position ⊳ xi to the final position xf. Example 5.4 In a ballistics demonstration a police officer fires a bullet of mass 50.0 g If the displacements are allowed to approach with speed 200 m s-1 (see Table 5.2) on soft zero, then the number of terms in the sum plywood of thickness 2.00 cm. The bullet increases without limit, but the sum approaches emerges with only 10% of its initial kinetic a definite value equal to the area under the curve energy. What is the emergent speed of the in Fig. 5.3(b). Then the work done is bullet ? xf W = lim F (x )∆xAnswer The initial kinetic energy of the bullet ∆ x → 0 ∑ x i is mv2/2 = 1000 J. It has a final kinetic energy xfof 0.1×1000 = 100 J. If vf is the emergent speed x ) d x (5.7)of the bullet, = ∫F ( i 1 2 x mv f = 100 J where ‘lim’ stands for the limit of the sum when 2 ∆x tends to zero. Thus, for a varying force 2 × 100 J the work done can be expressed as a definite v f = 0. 05 kg integral of force over displacement (see also Appendix 3.1). = 63.2 m s–1 The speed is reduced by approximately 68% (not 90%). ⊳