Anyone send me some mcqs in chapter - 11 Work and energy in physics for class 9.
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Answers
Answer:
1. A man is carrying the heavy luggage from one platform to the other of a Railway station but still according to the logics of science his work done is said to be zero. Can you opt out the correct reason?
(a) The force is acting along the direction of displacement of luggage
(b) The force is acting perpendicular to the direction of displacement of luggage
(c) The force is acting opposite to the direction of displacement of luggage
(d) None of these
Answer: (b) The force is acting perpendicular to the direction of displacement of luggage
2. When a body falls freely towards the earth, then its total energy
(a) Decreases
(b) Increases
(c) First increases and then decreases
(d) Remains constant
Answer: (d) Remains constant
3. When a body like earth is moving in a circular path the work done in that case is zero because:
(a) Centripetal force acts in the direction of motion of the body
(b) Centripetal force acts along the radius of circular path
(c) Gravitational force acts along the radius of circular path
(d) Centrifugal force acts perpendicular to the radius of circular pathAnswer: (b) Centripetal force acts along the radius of circular path
4. A car is accelerated on a leveled road and attains a velocity 4 times of its initial velocity. In this process, the kinetic energy of the car
(a) Becomes twice to that of the initial
(b) Becomes four times to that of the initial
(c) Remains the same
(d) Becomes 16 times to that of the initial
Answer: (d) Becomes 16 times to that of the initial
Answer:
Answer
MCQ Work And Energy Class 9 Question 10.
The number of joules contained in 1 kWh is
(a) 36 × 105 J
(b) 3.6 × 107 J
(c) 36 × 108 J
(d) 3.7 × 107 J
Work Energy And Power Class 9 MCQ Question 11.
Two army persons A and B each of weight of 500 N climb up a rope through a height of 10 m. A takes 20 s while B takes 40 s to achieve this task. What is ratio of the powers of person A and B?
(a) 1 : 2
(b) 1 : 4
(c) 2 : 1
(d) 14 : 1
Question 12.
Which of the following graphs best represents graphical relation between momentum P and kinetic energy K for a body in motion?
Question 13.
If speed of a car becomes 2 times, its kinetic energy becomes
(a) 4 times
(b) 8 times
(c) 16 times
(d) 12 times
Question 14.
Work done by friction
(a) increases kinetic energy of body
(b) decreases kinetic energy of body
(c) increases potential energy of body
(d) decreases potential energy of body.
Question 15.
When a coil spring is compressed, the work is done on the spring. The elastic potential energy
(a) increases
(b) decreases
(c) disappears
(d) remains unchanged
Question 16.
One joule work is said to be done when
(a) a force of 1 N displaces a body by 1 cm
(b) a force of 1 N displaces a body by 1 m
(c) a force of 1 dyne displaces a body by 1 m
(d) a force of 1 dyne displaces a body by 1 cm.
Question 17.
SI unit of power is
(a) watt
(b) joule
(c) newton
(d) metre
Question 18.
Mechanical energy of a body includes
(a) kinetic energy only
(b) potential energy only
(c) kinetic energy and potential energy
(d) none of these
Question 19.
Commercial unit of energy is
(a) joule
(b) kWh
(c) watt
(d) newton
Question 20.
Potential energy of a body depends on its
(a) position
(b) configuration
(c) position and configuration
(d) mass and velocity
Fill in the blanks
1. Work done is product of ………….. and distance moved the direction of the force.
Answer
2. If the angle between force and displacement is …………. then work done is said to be zero.
Answer
3. Energy of a body is defined as the capacity or …………. to do work.
Answer
4. Mechanical energy includes ………….. and ……………
Answer
5. Energy can neither be ………….. nor ………….. it can only transformed from one form to another.
Answer
6. ………….. is defined as the rate of doing work.
Answer
7. Commercial unit of energy is ………………
Match the following columns
Column A Column B
(a) SI unit of power (i) 1/2 mv2
(b) Kinetic energy (ii) The change of one form of energy into another
(c) Potential energy (iii) watt
(d) SI unit of work (iv) If applied force on an object and displacement is in opposite direction.
(e) Negative work (v) Energy possessed by a body due to its position or configuration.
(f) Power (vi) Joule
(g) Expression of kinetic energy (vii) Energy possessed by a body due to its motion.
(h) Transformation of energy (viii) Rate of doing work