(Solved): EXERCISE - 1 PART-I PROJECTILE MOTION : OBJECTIVE QUESTIONS "Marked Questions are having more than ...

EXERCISE - 1 PART-I PROJECTILE MOTION : OBJECTIVE QUESTIONS "Marked Questions are having more than one correct option. Section (A) : Definition, Projectile on a horizontal plane A-1. A particle move along the parabolic path $$x=y^2+2y+2$$ in such a way that the $$y$$-component of velocity vector remains $$5\mathrm{m}/\mathrm{s}$$ during the motion. The magnitude of the acceleration of the particle is : (A) $$50\mathrm{m}/{\mathrm{s}}^2$$ (B) $$100\mathrm{m}/{\mathrm{s}}^2$$ (C) $$10\sqrt{2}\mathrm{m}/{\mathrm{s}}^2$$ (D) $$0.1\mathrm{m}/{\mathrm{s}}^2$$ A-2. If 4 seconds be the time in which a projectile reaches a point $$P$$ of its path and 5 seconds the time from $$P$$ till it reaches the horizontal plane through the point of projection. The height of $$\mathrm{P}$$ above the horizontal plane will be - $$\left[g=9.8\mathrm{m}/{\sec }^2\right]$$ (A) 98 meters (B) 49 meters (C) 196 meters (D) 147 meters A-3. During projectile motion, acceleration of a particle at the highest point of its trajectory is : (A) $$g$$ (B) zero (C) less than $$g$$ (D) dependent upon projection velocity A-4. In case of an oblique projectile, the velocity is perpendicular to acceleration : (A) Once only (B) Twice (C) Never (D) Four times A-5. The velocity of projection of a projectile is $$(6\hat{i}+8\hat{j}){\mathrm{ms}}^{?1}$$. The horizontal range of the projectile is : (A) $$4.9\mathrm{m}$$ (B) $$9.6\mathrm{m}$$ (C) $$19.6\mathrm{m}$$ (D) $$14\mathrm{m}$$ A-6. A projectile is fired with velocity u making angle $$?$$ with the horizontal. What is the change in velocity (from initial) when it is at the highest point : (A) $$u\cos ?$$ (B) $$u$$ (C) $$u\sin ?$$ (D) $$(u\cos ??u)$$ A-7. A projectile can have the same range $$R$$ for two angles of projection. If $$t_1$$ and $$t_2$$ be the times of flight in two cases, then the product of two times of flight is : (A) $$t_1{t}_2?R^2$$ (B) $$t_1{t}_2?R$$ (C) $$t_1{t}_2?\frac{1}{R}$$ (D) $${\mathrm{lot}}_2?\frac{1}{R^2}$$ A-8.* In case of projectile motion if two projectiles $$A$$ and $$B$$ are projected with same speed at angles $$15^{?}$$ and $$75^{?}$$ respectively to the horizontal then : (A) $${\mathrm{H}}_{\mathrm{A}}>{\mathrm{H}}_{\mathrm{B}}$$ (B) $${\mathrm{H}}_{\mathrm{A}}<{\mathrm{H}}_{\mathrm{B}}$$ (C) $$T_A>T_B$$ (D) $$T_A<T_B$$ A-9. Four bodies $$\mathrm{P},\mathrm{Q},\mathrm{R}$$ and $$\mathrm{S}$$ are projected with equal velocities having angles of projection $$15^{?},30^{?},45^{?}$$ and $$60^{?}$$ with the horizontal respectively. The body having shortest range is : (A) $$P$$ (B) $$\mathrm{Q}$$ (C) $$R$$ (D) $$\mathrm{S}$$ A-10. If for a given angle of projection, the horizontal range is doubled, the time of flight becomes : (A) 4 times (B) 2 times (C) $$\sqrt{2}$$ times (D) $$1/\sqrt{2}$$ times A-11. A projectile is fired with a speed $$\mathrm{u}$$ at an angle $$?$$ with the horizontal. Its speed when its direction of motion makes an angle ' $$?$$ ' with the horizontal is : (A) $$u\sec ?\cos ?$$ (B) u $$\sec ?\sin ?$$ (C) $$\mathrm{u}\cos ?\sec ?$$. (D) $$u\sin ?\sec ?$$