11th Physics - Book Back Answers - Unit 4 - English Medium Guides

 

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Tamil Nadu Board 11th Standard Physics - Unit 4: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 4 – Physics from the Tamil Nadu State Board 11th Standard Physics textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Physics Unit 4 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 11 students! Prepare well and aim for top scores. Thank you!

Unit 4:Work Energy And Power

I. Multiple Choice Questions

1. A uniform force of  $(\widehat{2\mathrm{i}}+\widehat{\mathrm{j}})\mathrm{N}$ acts on a particle of mass 1 kg. The particle displaces from position $(\widehat{3\mathrm{j}}+\widehat{\mathrm{k}})$  m to $$$(5\widehat{\mathrm{i}}+3\widehat{\mathrm{j}})$$\stackrel{}{\mathbf{}}$$\stackrel{}{\mathbf{ }}$m. The work done by the force on the particle is (AIPMT model 2013)
(a) 9 J
(b) 6 J
(c) 10 J 
(d) 12 J
Answer Key:
(c) 10 J 

2. A ball of mass 1 kg and another of mass 2 kg are dropped from a tall building whose height is 80 m. After, a fall of 40 m each towards Earth, their respective kinetic energies will be in the ratio of
(AIPMT model 2004)
(a) $\sqrt{2}$ : 1 
(b) 1 : $\sqrt{2}$
(c) 2 : 1 
(d) 1 : 2
Answer Key:
(d) 1 : 2

3. A body of mass 1 kg is thrown upwards with a velocity 20 ms⁻¹. It momentarily comes to rest after attaining a height of 18 m. How much energy is lost due to air friction?(Take g = 10ms⁻² ) 
(AIPMT 2009)
(a) 20 J
(b) 30 J
(c) 40 J
(d) 10 J
Answer Key:
(a) 20 J 

4. An engine pumps water continuously through a hose. Water leaves the hose with a velocity v and m is the mass per unit length of the water of the jet. What is the rate at which kinetic energy is imparted to water?(AIPMT 2009)
(a) $\frac{1}{2}m{v}^3$
(b) mv³
(c) $\frac{3}{2}m{v}^2$ 
(d) $\frac{5}{2}m{v}^2$
Answer Key:
(a) $\frac{1}{2}m{v}^3$

5. A body of mass 4 m is lying in xy-plane at rest. It suddenly explodes into three pieces. Two pieces each of mass m move perpendicular to each other with equal speed v. The total kinetic energy generated due to explosion is  (AIPMT 2014)
(a) mv² 
(b) $\frac{3}{2}m{v}^2$
(c) 2 mv²
(d) 4mv²
Answer Key:
(b)  $\frac{3}{2}m{v}^2$

6. The potential energy of a system increases, if work is done
(a) by the system against a conservative force
(b) by the system against a non-conservative force
(c) upon the system by a conservative force
(d) upon the system by a non-conservative force
Answer Key:
(a) by the system against a conservative force

7. What is the minimum velocity with which a body of mass m must enter a vertical loop of radius R so that it can complete the loop?.
(a) $\sqrt{2gR}$
(b) $\sqrt{3gR}$
(c) $\sqrt{5gR}$
(d) $\sqrt{gR}$
Answer Key:
(c) 5gR 

8. The work done by the conservative force for a closed path is
(a) always negative
(b) zero
(c) always positive
(d) not defined
Answer Key:
(b) zero

9. If the linear momentum of the object is increased by 0.1%, then the kinetic energy is increased by
(a) 0.1 % 
(b) 0.2%
(c) 0.4% 
(d) 0.01%
Answer Key:
(b) 0.2%

10. If the potential energy of the particle is $\alpha -\frac{\beta }{2}{x}^2$ 2 , then force experienced by the particle is
(a) $F=\frac{\beta }{2}{x}^2$
(b) $F=\beta x$
(c) $F=-\beta x$
(d)$\mathrm{ F}=-\frac{\beta }{2}{x}^2$
Answer Key:
(b) $F=\beta x$

11. A wind-powered generator converts wind energy into electric energy. Assume that the generator converts a fixed fraction of the wind energy intercepted by its blades into electrical energy. For wind speed v, the electrical power output will be proportional to

(a) v

(b) v²

(c) v³

(d) v⁴

Answer Key:
(c) v³

12. Two equal masses m₁ and m₂ are moving along the same straight line with velocities 5ms^-1and -9ms^-1 respectively. If the collision is elastic, then calculate the velocities after the collision of m₁ and m₂, respectively

(a) -4ms^-1 and 10 ms^-1

(b) 10ms^-1 and 0 ms^-1

(c) -9ms^-1 and 5 ms^-1

(d) 5 ms^-1 and 1 ms^-1

Answer Key:
(c) -9ms^-1 and 5 ms^-1

13. A particle is placed at the origin and a force F = kx is acting on it (where k is a positive constant). If U(0)= 0, the graph of U (x) versus x will be (where U is the potential energy function) (IIT 2004)

Answer Key:

14. A particle which is constrained to move along x-axis, is subjected to a force in the same direction which varies with the distance x of the particle from the origin as F(x)=-kx+ax³. Here, k and a are positive constants. For x ≥ 0, the functional form of the potential energy U(x) of the particle is

(IIT 2002)

Answer Key:

 

15. A spring of force constant k is cut into two pieces such that one piece is double the length of the other. Then, the long piece will have a force constant of

(a) $\frac{2}{3}\mathrm{k}$
(b) $\frac{3}{2}\mathrm{k}$
(c) 3k
(d) 6k
Answer Key:
(b) $\frac{3}{2}\mathrm{k}$

$\mathrm{ }$

II. Short Answer Questions

11th physics

III. Long Answer Questions

11th Physics

IV. Exercise

11th Physics