# Important Physics MCQS For CSS PMS PPSC FPSC NTS SET 6

Read important Physics MCQS For Exam.These physics  General Knowledge Mcqs Contain  of World Geography, Atmosphere, Science & Literature, events Mcqs, Current Affairs Mcqs , Pakistan Affairs Mcqs and International Organizations. These general knowledge questions are very important for all type of exams conducted by Fpsc, Nts, Kppsc, Ppsc, Spsc, Bpsc, Ots, Uts, Pts, Cts, Ats, etea and other testing agencies of Pakistan

##### Note: The bold option is the right answer for the given MCQ’S:

1. A vector in the xy plane has a magnitude of 25 m and an x component of 12 m. The angle it
makes with the positive x axis is:
A. 26◦
B. 29◦
C. 61◦
D. 64◦
E. 241◦

2. The angle between An = (25 m)ˆi + (45 m)ˆj and the positive x axis is:
A. 29◦
B. 61◦
C. 151◦
D. 209◦
E. 241◦

3. The angle between An = (−25 m)ˆi + (45 m)ˆj and the positive x axis is:
A. 29◦
B. 61◦
C. 119◦
D. 151◦
E. 209◦

4. Let An = (2 m)ˆi+ (6 m)ˆj−(3 m) ˆk and Bn = (4 m)ˆi+ (2 m)ˆj+ (1 m) ˆk. The vector sum Sn = An +Bn is:
A. (6 m)ˆi + (8 m)ˆj − (2 m) ˆk
B. (−2 m)ˆi + (4 m)ˆj − (4 m) ˆk
C. (2 m)ˆi − (4 m)ˆj + (4 m) ˆk
D. (8 m)ˆi + (12 m)ˆj − (3 m) ˆk

E. none of these

5. Let An = (2 m)ˆi + (6 m)ˆj − (3 m) ˆk and Bn = (4 m)ˆi + (2 mˆj + (1 m) ˆk. The vector differenceDn = An − Bn is:
A. (6 m)ˆi + (8 m)ˆj − (2 m) ˆk
B. (−2 m)ˆi + (4 m)ˆj − (4 m) ˆk
C. (2 m)ˆi − (4 m)ˆj + (4 m) ˆk
D. (8 m)ˆi + (12 m)ˆj − (3 m) ˆk

E. none of these

6. If An = (2 m)ˆi − (3 m)ˆj and Bn = (1 m)ˆi − (2 m)ˆj, then An − 2Bn =
A. (1 m)ˆj
B. (−1 m)ˆj
C. (4 m)ˆi − (7 m)ˆj
D. (4 m)ˆi + (1 m)ˆj
E. (−4 m)ˆi + (7 m)ˆj

7. A certain vector in the xy plane has an x component of 4 m and a y component of 10 m. It is
then rotated in the xy plane so its x component is doubled. Its new y component is about:
A. 20 m
B. 7.2 m
C. 5.0 m
D. 4.5 m
E. 2.2 m

8. Vectors An and Bn each have magnitude L. When drawn with their tails at the same point, the
angle between them is 30◦. The value of An · Bn is:
A. zero
B. L2
C. √3L2/2
D. 2L2
E. none of these

9. Let An = (2 m)ˆi + (6 m)ˆj − (3 m) ˆk and Bn = (4 m)ˆi + (2 m)ˆj + (1 m) ˆk. Then An · Bn =

A. (8 m)ˆi + (12 m)ˆj − (3 m) ˆk
B. (12 m)ˆi − (14 m)ˆj − (20 m) ˆk

C. 23 m2
D. 17 m2
E. none of these

10. Two vectors have magnitudes of 10 m and 15 m. The angle between them when they are drawn
with their tails at the same point is 65◦. The component of the longer vector along the line of
the shorter is:
A. 0
B. 4.2 m
C. 6.3 m
D. 9.1 m
E. 14 m

11. Let Sn = (1 m)ˆi + (2 m)ˆj + (2 m) ˆk and Tn = (3 m)ˆi + (4 m) ˆk. The angle between these two

vectors is given by:
A. cos−1(14/15)
B. cos−1(11/225)
C. cos−1(104/225)
D. cos−1(11/15)
E. cannot be found since Sn and Tn do not lie in the same plane

12. Two vectors lie with their tails at the same point. When the angle between them is increased
by 20◦ their scalar product has the same magnitude but changes from positive to negative.
The original angle between them was:
A. 0
B. 60◦
C. 70◦
D. 80◦
E. 90◦

13. If the magnitude of the sum of two vectors is less than the magnitude of either vector, then:
A. the scalar product of the vectors must be negative
B. the scalar product of the vectors must be positive
C. the vectors must be parallel and in opposite directions
D. the vectors must be parallel and in the same direction
E. none of the above

14. If the magnitude of the sum of two vectors is greater than the magnitude of either vector, then:
A. the scalar product of the vectors must be negative
B. the scalar product of the vectors must be positive
C. the vectors must be parallel and in opposite directions
D. the vectors must be parallel and in the same direction
E. none of the above

15. Vectors An and Bn each have magnitude L. When drawn with their tails at the same point, the
angle between them is 60◦. The magnitude of the vector product An × Bn is:
A. L2/2
B. L2
C. √3L2/2
D. 2L2
E. none of these

16. Two vectors lie with their tails at the same point. When the angle between them is increased
by 20◦ the magnitude of their vector product doubles. The original angle between them was
A. 0
B. 18◦
C. 25◦
D. 45◦
E. 90◦

17. Two vectors have magnitudes of 10 m and 15 m. The angle between them when they are drawn
with their tails at the same point is 65◦. The component of the longer vector along the line
perpendicular to the shorter vector, in the plane of the vectors, is:
A. 0
B. 4.2 m
C. 6.3 m
D. 9.1 m
E. 14 m

18. The two vectors (3 m)ˆi − (2 m)ˆj and (2 m)ˆi + (3 m)ˆj − (2 m) ˆk define a plane. It is the plane of
the triangle with both tails at one vertex and each head at one of the other vertices. Which of
the following vectors is perpendicular to the plane?
A. (4 m)ˆi + (6 m)ˆj + (13 m) ˆk
B. (−4 m)ˆi + (6 m)ˆj + (13 m) ˆk
C. (4 m)ˆi − (6 m)ˆj + (13 m) ˆk
D. (4 m)ˆi + (6 mˆj − (13 m) ˆk
E. (4 m)ˆi + (6 m)ˆj

19. Let Rn = Sn × Tn and θ W= 90◦, where θ is the angle between Sn and Tn when they are drawn with
their tails at the same point. Which of the following is NOT true?
A. |Rn | = |Sn||Tn|sin θ
B. −Rn = Tn × Sn
C. Rn · Sn = 0
D. Rn · Tn = 0
E. Sn · Tn = 0

20. The value of ˆi · (ˆj × ˆk) is:

A. zero
B. +1
C. −1
D. 3
E. √3