## Thursday, 6 April 2017

### 1st year Physics Chapter 2 Vectors and scalar MCQs

PHYSICS              CHAPTER 2

1. Which one of the followings is a scalar?
(a) Energy   (b) Velocity
(c) Force   (d) Torque

2. Which one of the followings is a vector?
(a) Length   (b) Volume
(c) Velocity   (d) Work

3. In which one of the followings are all the three quantities vectors?
(a) Displacement, velocity, energy
(b) Force, work, energy
(c) Displacement, velocity, momentum
(d) Velocity, acceleration, power

4. The reverse process of adding two vectors is called
(a) multiplication (b) subtraction
(c) resolution     (d) none of these

5. The resultant of two vectors of equal magnitude inclined at some angle is equal to the magnitude of either of the two vectors. The angle between the two is
(a) 60°   (b)90°
(c) 120°   (d) 180°

6. Tick the answer which is correct for     R = A + B.

7. Which figure represents   R = U – V?

8. The result of adding   A into – A is
(a) A (b) 2 A
(c)  O (d) 0

9. The unit vector of a vector   A is given by
^ ^ A
(a) A  = A A (b) A  =
A
^ A ^ A
(c) A  =   (d) A  =
A A
10. When a certain vector is multiplied by – 1, then the direction of the vector changes through
(a) 90°   (b) 120°
(c) 150°     (d) 180°

11. Rectangular components make an angle of
(a) 0°   (b) 60°
(c) 90°   (d) 120°

(a) 1   (b) 2
(c) 3   (d) 4

13. One of the rectangular components of a velocity of
50 ms-1 is 30 ms-1. The other component in ms-1 is
(a) 15   (b) 20
(c) 25   (d) 40

^ ^
14. For the two vectors  Ax = (20 N) i ,  Ay= (20 N) j , the angle made by the resultant vector A with the x-axis is
(a) 45°   (b) 135°
(c) 215°   (d) 315°

15. Which of the following forces cannot be added to give of a resultant of 2 N?
(a) 1 N and 1 N   (b) 1 N and 2 N
(c) 2   N and 2  N   (d) 1 N and 3 N

17. Two forces act together on an object. The magnitude of their resultant is least when the angle between them is
(a) 45°   (b) 60°
(c) 90°   (d) 180°

18. If  |A+B| = |A – B| where A and B are two vectors of equal magnitudes, then the angle between A and B is
(a) 0°   (b) 60°
(c) 90°   (d) 180°

^ ^
19. The angle subtended by r = 3 i  + 4 j   with x-axis is
(a) 53°   (b) 30°
(c) 41°   (d) 60°

^ ^
20. The magnitude of a vector  A = Ax i  –  Ay j  is
(a) A2x  + A2y   (b) Ax2 + A2y
(c) A2x  – A2y   (d) A2x – A2y

21. The dot product of two non-zero vectors equals the product of their magnitudes only if the angle between them is
(a) 0°   (b) 90°   (c) 120°   (d) 180°

22. For which of the followings pair of angles, the dot product of two vectors is equal to the one half of the product of  magnitudes of two vectors?
(a) 60° and 120°   (b) 60° and 240°
(c) 60° and 300° (d) none of these

23. For a vector A,
(a) A •  A = 0 (b)  A •  A = 1
(c)  A • A = A (d)  A •  A = A2

24. Which one of the followings is correct?
^ ^ ^ ^ ^
(a) i  •  j  =  k   (b) i  •  j  = 0
^ ^ ^ ^ ^
(c) i  •  j  =  1   (d) i  •  j  = –k

^ ^ ^
25. Given A = 2i – 2j + k  , the magnitude of this vector is
(a) 1   (b) 2
(c) 3   (d) 5

26. If A  B lies along + z-axis, the vectors   A and B will be in
(a) xz-plane   (b) xy-plane
(c) yz-plane         (d) x-direction only

27. The cross product of two non-zero parallel vectors  A and B is
(a) AB sin    (b) AB
^
(c) AB sin      (d) O

^ ^ ^ ^
29. If A = Ax i  + Ay j  and B = Bx i  + By j  are two non-
parallel vectors, then the direction of A  B is along
(a) A (b)  B
(c) x-axis   (d) z-axis

^ ^ ^ ^
30. If A = A1 i  + A2 j  and B = B1 i  + B2 j , the number of components in the vector  A  B is
(a) 1 only   (b) 2 only
(c) 3 only   (d) 4 only

31. If A • B = 0 and A  B = 0, then
(a) either A or B is a null vector.
(b) A and B are non-parallel.
(c) A and B are perpendicular to each other.
(d) A and B are parallel to each other.

32. The vector product is
(a) commutative   (b) anticommutative

33. The cross product of two vectors has a magnitude equal to the product of their magnitudes. Their dot product is equal to
(a) AB sin  (b) AB cos
(c) AB (d) 0

34. Torque produced by a force depends upon
(a) magnitude of the force and the angular velocity
(b) magnitude of the force and displacement   (c) magnitude of the force and moment arm         (d) force and acceleration of the body.

35. A couple consists of
(a) two equal and opposite forces acting at two different points on the body
(b) two equal and parallel forces acting at two different points  (c) two equal and opposite force acting at a point on the body  (d) two equal and parallel force acting at a point on the body.

36. The arm of a couple is
(a) any distance between the forces
(b) the shortest distance between the forces
(c) perpendicular distance between the two forces     (d)     the longest distance between the two forces.

37. If the resultant of all the forces acting on a  body is zero, then the body
(a) has angular momentum (b)  has acceleration
(c)  is at rest   (d) is in translational equilibrium

38. Three coplanar forces acting on a body keep it in equilibrium. The forces must be
(a) collinear   (b) concurrent
(c) non-concurrent (d) parallel

39. If the line of action of the force passes through the axis of rotation, then the torque is
(a) zero (b) maximum
(c) clockwise in direction (d) counter clockwise in direction

40. ˆi . (ˆj * k)ˆ equals
(a) ˆi (b) kˆ
(c) 1   (d)  0

Key to Test Chapter 2

1 a 21
2 c 22
3 c 23
4 c 24
5 c 25
6 d 26
7 b 27
8 c 28
9 c 29
10 d 30
11 c 31
12 c 32
13 d 33
14 a 34
15 b 35
16 a 36
17 d 37
18 c 38
19 a 39
20 b 40