Physics-DPP-4-Kinematics

PHYSICS Topic: KINEMATICS Date: 1. Which of the following is a scalar quantity? (a) Work (b) Displacement (c) Velocity (d) Acceleration 2. Which of the following operations make no sense in case of scalars and vectors? (a) Multiplying any vector by a scalar (b) Adding a component of vector to the same vector (c) Multiplying any two scalars (d) Adding a scalar to a vector of the same dimensions. 3. The minimum number of coplanar vectors of unequal magnitude required to produce a zero resultant is : (a) 2 (b) 3 (c) 4 (d) more than 4 r r r r r r 4. The vectors A and B are such that A + B = A – B then the angle between the two vectors A and B will be (a) 0o (b) 60o (c) 90o (d) 180o ur ur ur ur ur ur ur ur 5. If A = B + C and the magnitudes of A, B and C are 5, 4 and 3 units respectively, the angle between A and C is : (a) cos–1 æç3ö÷ (b) cos–1 æç4ö÷ π (c) (d) sin–1 æç3ö÷ ç ÷ ç ÷ 2 ç ÷ è5ø è5ø è4ø 6. Two forces each numerically equal to 10 dynes are acting as shown in the following figure, then the resultant is : (a) 10 dynes (b) 20 dynes (c) 10 dynes (d) 5 dynes 7. A particle is moving eastward with a velocity of 5 m/s. In 10 seconds, the velocity changes to 5 m/s northwards. The average acceleration in this time is : (a) zero (b) m/sec2 towards north-west (c) m/sec2 towards north-east (d) 1 m/sec2 towards north-west (e) 1 m/sec2 towards north. 2 2 r r r 8. Figure shows three vectors a, b and c , where R is the mid-point of PQ. Then which of the following relations is correct ? (a) r r r a + b = 2 c r r r r r r (b) a + b = c r r r (c) a – b = 2c (d) a – b = c 9. If a vector 2 ˆi + 3ˆj + 8kˆ is perpendicular to the vector 4 ˆj – 4 iˆ + αkˆ , then the value of α is : 1 (a) – 1 (b) 2 (c) – 1 2 (d) 1 10. If three vectors along co-ordinate axes represent the adjacent sides of a cube of length b, then the unit vector along its diagonal passing through the origin will be : (a) (b) (c) ˆ ˆ ˆ (d) i + j + k PHYSICS Topic: KINEMATICS Date: Answer Key 1. (a) 2. (d) 3. (b) 4. (c) 5. (a) 6. (c) 7. (c) 8. (a) 9. (c) 10. (d)

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