Physics-DPP-6-Kinematics

PHYSICS Topic: KINEMATICS Date: 1. At what angle θ to the horizontal should an object be projected, so that the maximum height reached is equal to the horizontal range (a) tan–1 (2) (b) tan–1 (4) (c) tan–1 æç2ö÷ (d) tan–1 (3) ç ÷ è3ø 2. If T1 & T2 are the time of flights for two complementary angles, then the range of projectile R is given by : (a) R = gT1T2 4 (b) R = gT1T2 2 (c) R = gT1T2 3 v (d) R = 2gT1T2 3 3. Two projectiles A and B are thrown from the same point with velocities v and 2 respectively. If B is thrown at an angle 45o with horizontal, what is the inclination of A if their ranges are the same ? (a) 45o (b) 30o (c) 60o (d) None 4. The height y and distance x along the horizontal for a body projected in the x - y plane are given by y = 8t – 5t2 and x = 6t. The initial speed of projection is : æç10ö÷ (a) 8 m/s (b) 9 m/s (c) 10 m/s (d) ç ÷m/s 5. The equation of motion of a projectile is : What is the range of the projectile ? y = 12x – 3 x2 4 è 3 ø (a) 12 m (b) 16 m (c) 20 m (d) 24 m 6. A ball is thrown at different angles with the same speed u and from the same point. It has the same range in both the cases. If y1 and y2 be the heights attained in the two cases, then y1 + y2 = ... (a) u2 g (b) 2u2 g (c) u2 u2 2g (d) 4g 7. A particle is thrown with a speed u at an angle θ with the horizontal. When the particle makes an angle  with the horizontal, its speed changes to v where : (a) v = u cosθ sin α (b) v = u cosθ cos α (c) v = u cosθ secα (d) v = u secθ tan α 8. Two projectiles Aand B are projected with same speed at angles 30o and 60o to the horizontal then, which one is wrong : (a) RA = RB (b) HB = 3 HA (c) TB = 3 TA (d) none of these 9. The initial velocity of a particle of mass 2 kg is (4 iˆ + 4 ˆj)m/s . A constant force of – 20 ˆj N is applied on the particle. Initially the particle was at (0, 0). Find the x- coordinate of the point where its y-coordinate is again zero. (a) 3.2 m (b) 6 m (c) 4. 8 m (d) 1. 2 m 10. Two particles are simultaneously projected in opposite directions horizontally from a given point in space where gravity g is uniform. If u1 and u2 be their initial speeds, then the time t after which their velocities are mutually perpendicular is given by : (a) g (b) (b) g (c) g (d) g PHYSICS Topic: KINEMATICS Date: Answer Key 1. (b) 2. (b) 3. (b) 4. (c) 5. (b) 6. (c) 7. (c) 8. (d) 9. (a) 10. (a)

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