Physics-DPP-5-Kinematics

PHYSICS Topic: KINEMATICS Date: ur ur ur ur ur 1. The resultant of A and B is R1 . On reversing the vector B , the resultant becomes R . What is the value of R 2 + R 2 ? 2 1 2 (a) A2 + B2 (b) A2 – B2 (c) 2 (A2 + B2) (d) 2 (A2 – B2) r r r r r r 2. If F1 and F2 are 2 vectors of equal magnitudes F such that F1 . F2 = F1 ´ F2 , then F1 + F2 is equal to : (b) 2 F (c) F (d) none of these 3. A vector having magnitude 30 unit makes equal angles with each of X, Y and Z axes. The components of vector along each of X, Y and Z axes are : (a) 10 units (b) unit (c) 15 3 unit (d) 10 unit 4. The value of n so that vectors 2iˆ + 3 ˆj – 2kˆ , 5 iˆ + nˆj – kˆ and – iˆ + 2 ˆj + 3kˆ may be coplanar, will be : (a) 18 (b) 28 (c) 9 (d) 36 r r r r r r 5. If a and b are two vectors then the value of (a + b )´ (a – b) is : r r r r r r r r (a) 2(b ´ a) (b) –2(b ´ a) (c) b ´ a (d) a ´ b 6. The resultant of two forces 3 P and 2 P is R. If the first force is doubled then the resultant is also doubled. The angle between the two forces is : (a) 60o (b) 120o (c) 70o (d) 180o r r r r r r 7. If A ´ B = 3 A.B , then the value of A + B is : (a) (A2 + B2 + 1/ 2 AB æ 2 (b) çA + è / 2 B2 + (c) (A + B) (d) (A2 + B2 + 1/ 2 3AB 8. If a vector p is making angles α,β and γ respectively with the X, Y and Z axes, then sin2 α + sin2 β + sin2 γ is equal to : (a) zero (b) 1 (c) 2 (d) 3 9. If vectors r r A and B have an angle θ between them, then value of Aˆ – Bˆ will be : (a) 2 cos θ 2 (b) 2 tan θ 2 (c) (c) 2 sin θ 2 (d) none of these 10. If a iˆ + bˆj is a unit vector and it is perpendicular to iˆ + ˆj , then the value of a and b is : (a) 1, 0 (b) – 2 , 0 (c) 0.5, – 0.5 (d) none of these PHYSICS Topic: KINEMATICS Date: Answer Key 1. (c) 2. (a) 3. (a) 4. (a) 5. (a) 6. (b) 7. (a) 8. (c) 9. (b) 10. (d)

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