MCQ Questions for Class 11 Physics Chapter 4 Motion In A Plane

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MCQ Questions for Class 11 Physics Chapter 4 Motion In A Plane

Q.1. Which of the following conditions are sufficient and essential for a quantity to be a vector?
(a) Magnitude and direction
(b) Magnitude and addition, subtraction, multiplication by ordinary rules of algebra
(c) Magnitude, direction, and addition, subtraction multiplication and division by vector laws
(d) Magnitude, direction and combination of vectors by ordinary rules of algebra

Answer Answer: (c) A vector quantity is defined as the quantity which has magnitude and direction and for which all the mathematical operations are possible only through vector laws of algebra.

Q.2. A scalar quantity is one that
(a) can never take negative values
(b) has magnitude as well as direction
(c) does not vary from one point to another in space
(d) has the same value for observers with different orientations of axes.

Answer Answer: (d) A scalar quantity has only magnitude and the same value for observers with different orientations of axes.

Q.3. If T is the angle between two vectors, then the resultant vector is maximum, when value of T is
(a) 0°
(b) 90°
(c) 180°
(d) Same in all cases.

Answer Answer: (a)

Q.4. When a body moves with a constant speed along a circle
(a) no work is done on it
(b) no acceleration is produced in the body
(c) no force acts on the body
(d) its velocity remains constant

Answer Answer: (a)

Q.5. A body is travelling in a circle at a constant speed. It
(a) has a constant velocity
(b) is not accelerated
(c) has an inward radial acceleration
(d) has an outward radial acceleration

Answer Answer: (c)

Q.6. How many minimum number of vectors in different planes can be added to give zero resultant?
(a) 2
(b) 3
(c) 4
(d) 5

Answer Answer: (c) The resultant of any three vectors will be cancel out by Fourth vector

Q.7. Consider the quantities pressure, power, energy, impulse, gravitational potential, electric charge, temperature and area. Out of these, the vector quantities are
(a) impulse, pressure and area
(b) impulse and area
(c) area and gravitational potential
(d) impulse and pressure

Answer Answer: (b)

Q.8. Angular momentum is
(a) a scalar
(b) a polar vector
(c) an axial vector
(d) None of these

Answer Answer: (c)

Q.9. The shape of trajectory of the motion of an object is determined by
(a) acceleration
(b) initial position
(c) initial velocity
(d) All of these

Answer Answer: (d) The shape of the trajectory depends on the initial position, initial velocity and acceleration.

Q.10. If a particle moves in a circle describing equal angles in equal interval of time, its velocity vector
(a) remains constant
(b) changes in magnitude
(c) changes in direction
(d) changes both in magnitude and direction

Answer Answer: (c)

Q.11. Which of the following is an essential condition for horizontal component of projectile to remain constant?
(a) Acceleration due to gravity should be exactly constant
(b) Angle of projection should be 45°
(c) There should be no air-resistance
(d) All of these

Answer Answer: (c) Force due to viscosity, air – resistance are all dissipative forces. Thus in the presence of air – resistance the horizontal component of velocity will decrease, thus for horizontal component of velocity to remain constant, there should be no air-resistance

Q.12. In the projectile motion, if air resistance is ignored, the horizontal motion is at
(a) constant acceleration
(b) constant velocity
(b) variable acceleration
(d) constant retardation

Answer Answer: (b) If air resistance is ignored, then there is no acceleration in horizontal direction in projectile motion. Hence the particle move with constant velocity in horizontal direction.

Q.13. A moves with 65 km/h while B is coming back of A with 80 km/h. The relative velocity of B with respect to A is
(a) 80 km/h
(b) 60 km/h
(c) 15 km/h
(d) 145 km/h

Answer Answer: (c)

Q.14. The circular motion of a particle with constant speed is
(a) periodic but not simple harmonic
(b) simple harmonic but not periodic
(c) periodic and simple harmonic
(d) neither periodic nor simple harmonic

Answer Answer: (a)

Q.15. A bullet is dropped from the same height when another bullet is fired horizontally. They will hit the ground
(a) one after the other
(b) simultaneously
(c) depends on the observer
(d) None of these

Answer Answer: (b) In both the cases, the initial velocity in the vertical downward direction is zero. So they will hit the ground simultaneously.

Q.16. A hunter aims his gun and fires a bullet directly at a monkey on a tree. At the instant the bullet leaves the barrel of the gun, the monkey drops. Pick the correct statement regarding the situation.
(a) The bullet will never hit the monkey
(b) The bullet will always hit the monkey
(c) The bullet may or may not hit the monkey
(d) Can’t be predicted

Answer Answer: (b)

Q.17. What determines the nature of the path followed by a particle?
(a) Velocity
(b) Speed
(c) Acceleration
(d) None of these

Answer Answer: (c) The nature of path is determined by acceleration of particle. For example in uniform circular motion the transverse acceleration is zero & only radial acceleration acts. If radial acceleration is zero, then particle go in the direction in which transverse acceleration acts (if it is not zero).

Q.18. The time of flight of a projectile on an upward inclined plane depends upon
(a) angle of inclination of the plane
(b) angle of projection
(c) the value of acceleration due to gravity
(d) all of the above.

Answer Answer: (d)

Q.19. At the highest point on the trajectory of a projectile, its
(a) potential energy is minimum
(b) kinetic energy is maximum
(c) total energy is maximum
(d) kinetic energy is minimum.

Answer Answer: (d)

Q.20. The angle of projection, for which the horizontal range and the maximum height of a projectile are equal, is:
(a) 45°
(b) T = tan–14
(c) T = tan–1 (0.25)
(d) none of these.

Answer Answer: (b)

Q.21. For an object thrown at 45° to horizontal, the maximum height (H) and horizontal range (R) are related as
(a) R = 16 H
(b) R = 8 H
(c) R = 4 H
(d) R = 2H

Answer Answer: (c)

Q.22. A stone is just released from the window of a moving train moving along a horizontal straight track. The stone will hit the ground following a
(a) straight line path
(b) circular path
(c) parabolic path
(d) hyperbolic path

Answer Answer: (c) The horizontal velocity of the stone will be the same as that of the train. In this way, the horizontal motion will be uniform. The vertical motion will be controlled by the force of gravity. Hence it is accelerated motion. The resultant motion is a parabolic trajectory.

Q.23. Two bullets are fired horizontally with different velocities from the same height. Which will reach the ground first?
(a) Slower one
(b) Faster one
(c) Both will reach simultaneously
(d) It cannot be predicted

Answer Answer: (c) The time taken to reach the ground depends on the height from which the projectile is fired horizontally. Here height is same for both the bullets and hence they will reach the ground simultaneously

Q.24. A stone is projected with an initial velocity at an angle to the horizontal. A small piece separates from the stone before the stone reaches its maximum height. Then this piece will
(a) fall to the ground vertically
(b) fly side by side with the parent stone along a parabolic path
(c) fly horizontally initially and will trace a different parabolic path
(d) lag behind the parent stone, increasing the distance from it

Answer Answer: (b) The piece will fly side by side because the velocity of the piece is the same.

Q.25. At the top of the trajectory of a projectile, the acceleration is
(a) maximum
(b) minimum
(c) zero
(d) g

Answer Answer: (d) At the highest point of trajectory, the acceleration is equal to g.

Q.26. Centripetal acceleration is
(a) a constant vector
(b) a constant scalar
(c) a magnitude changing vector
(d) not a constant vector

Answer Answer: (d)

Q.27. The force required to keep a body in uniform circular motion is
(a) centripetal force
(b) centrifugal force
(c) resistance
(d) None of these

Answer Answer: (a)

Q.28. In a vertical circle of radius r at what point in the path a particle has tension equal to zero if it is just able to complete the vertical circle?
(a) Highest point
(b) Lowest point
(c) Any point
(d) At a point horizontally from the centre of circle of radius r

Answer Answer: (a)

Q.29. Two stones are moving with same angular speeds in the radii of circular paths 1 m and 2 m. The ratio of their linear speed is …X…. Here, X refers to
(a) 2
(b) 1/2
(c) 1/3
(d) 3

Answer Answer: (b)

Q.30. The direction of the angular velocity vector is along
(a) the tangent to the circular path
(b) the inward radius
(c) the outward radius
(d) the axis of rotation

Answer Answer: (d)

Q.31. In uniform circular motion
(a) both velocity and acceleration are constant
(b) acceleration and speed are constant but velocity changes
(c) both acceleration and velocity change
(d) both acceleration and speed are constant

Answer Answer: (c) In circular motion with constant speed, acceleration is always inward, its magnitude is constant but direction changes, hence acceleration changes, so does velocity. K.E. is constant.

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