PHYSICS-27-08 11th (J-Batch) WA

REVIEW TEST-2 Class : XI (J-Batch) Time : 100 min Max. Marks : 75 General Remarks: INSTRUCTIONS 1. The question paper contain 15 questions and 19 pages. All questions are compulsory. Please ensure that the Question Paper you have received contains all the QUESTIONS and Pages. 2. Each question should be done only in the space provided for it, and the answers should be neatly written in the blanks drawn at the end of each question, otherwise the solution will not be checked. 3. Use of Calculator, Log table and Mobile is not permitted. 4. Legibility and clarity in answering the question will be appreciated. 5. Put a cross ( × ) on the rough work done by you. Name Father's Name Class : Batch : B.C. Roll No. Invigilator's Full Name Useful Data: (i) sin 370 = 3/5; cos 370 = 4/5 ; tan370 = 3/4 (ii) sin 530 = 4/5 ; cos 530 = 3/5 ; tan530 = 4/3 (iii) g = 10m/s2 Important Instruction: Tampering with the answer sheet or changing the answers, after the answer sheet is evaluated will be strictly penalized. For Office Use ……………………………. Total Marks Obtained………………… Q.No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Marks Take g = 10 m/s2 whereever required in this paper. Q.1 In each case, fill in the box Y for yes and N for No (a) Can two vectors of unequal magnitude add up to zero? (b) Can three vectors of unequal magnitude add up to zero? (i) if they lie in a plane. (ii) if they do not lie in a plane. [1+1+1] Q.2 Kinetic energy of a particle moving on a circle is given as K = 1 X 2r2 2 where K is kinetic energy  the angular velocity (unit rad/s) r the radius X is a unknown physical quantity Find the physical quantity represented by X, using dimensional analysis. [3] Ans: _ Q.3 A mass 1kg moves in the x–y plane. Two forces F1 and F2, both in the x–y plane, are applied to the mass as shown, F1 = 10 N and F2 = 10 N. Find the acceleration vector of the mass. [3] Ans: a = Q.4 A lift is moving with uniform downward acceleration of 2m/s2. A ball is dropped inside the lift from a height 2 metre from the floor of lift. Find the time (t) after which ball will strike the floor. [3] Ans: _t_= Q.5 A “moving sidewalk” in an airport terminal moves at a speed of 1.0 m/s relative to the ground and is 80m long. A person runs on the side walk from its one end to the other at a speed of 4.0 m/s relative to the moving sidewalk in the same direction as the sidewalk. (a) How much time, t, does it take to exit the sidewalk? (b) Suppose the person performs a round trip on the sidewalk by moving from one end to the other and then returning back to the starting point, such that his speed always remains 4 m/s relative to the sidewalk.What is the total time (T) for such a round-trip? [3] Ans: (a) t = (b) _T = Q.6 A passenger who just missed the train stands on the platform, sadly watching the last two boggies of the train. The second last boggy takes time 3 sec. to pass by the passenger, and the last one takes time 2 sec. to pass by. How late is the passenger for the departure of the train? Assume that the train accelerates at constant rate. [3] Ans: Q.7 Velocity vector (in metre/sec) of a particle at any time t (in sec.) is given as V = 3t 2 iˆ + 3 ˆj  ˆ At t = 0 position of the particle is given as r0 = 2 j (m). Find the position vector of the particle at t = 2 sec and the average acceleration of the particle for t = 0 to t = 2 sec. [2+1] Ans: _r = a_a_v_g _= Q.8 Particle is observed to move along x axis according to relation x = t2 – 5t + 6 { x in m & t in sec}. Find (a) Times when particle is at origin. (b) Distance travelled between t = 0 & t = 3 sec. [2+4] Ans: (a) (b) Q.9 Sketch the position x and the acceleration a as a function of time for a ball whose velocity v as a function of time is shown. Use the same scale for the time axis of all graphs. The ball is located at x = 2 m when t = 0s. [2+4] Ans: Q.10 Lying on his back at the bottom of a slope that has an inclination of 30°, a soilder tries to hit the mark x metres upward along the slope with a gun as shown.Angle of the gun with the incline is 30°. Bullet strikes after 2 sec. Find the initial speed of bullet (u) and x. [3+3] Ans: _u_= x_= Q.11 Aball is thrown horizontally from a point O with speed 20 m/s as shown. Two seconds after the projection the ball strikes the incline plane at right angles to it. Find  (the angle of incline) and displacement (OP) of the ball. [3+3] Ans: __= OP = Q.12 A train is moving forward at a velocity of 2.0 m/s. At the instant the train begins to accelerate at 0.80 m/s2, a passenger drops a coin which takes 0.50 s to fall to the floor. (a) Calculate the height in the train from where it is dropped. (b) Where does it lands relative to a spot on the floor directly under the coin at release. (c) The dropped coin is viewed by an observer standing next to the tracks. By how much horizontal distance relative to this observer, the coin moves before landing. [2+2+2] Ans: (a) (b) (c) _ Q.13 A ball is thrown from origin at t = 0 at some angle. It is observed to have a height y above the ground described as a function of time as y = 10t – 5t2 and horizontal displacement x = 10 t. (a) What is the initial speed of the ball? (b) What is acceleration of the ball as a function of time? (c) What is the average velocity of the ball between t = 0 seconds and t = 1 seconds? (d) How much time elapses before the ball returns to the ground? [2+2+2+2] Ans: (a) (b) (c) (d) Q.14 Ball I is thrown towards a tower at an angle of 60° with the horizontal with unknown speed (u). At the same moment ball II is dropped from the top of tower as shown. Balls collide after two seconds and at the moment of collision, velocity of ball I is horizontal. Find (a) speed u. (b) distance of point of projection of ball I from base of tower (x). (c) height of tower (h) [3+2+3] Ans: (a)u = (b) _x = (c) _h = Q.15 Apolice officer sits on a parked motorcycle. A car travelling at a constant speed of 0 = 40.0 m/s passes by at t =0. At that same instant (t =0), the officer accelerates the motorcycle at a constant rate, and at time t1 = 20.0s overtakes the speeder. (a) (i) Find the acceleration (a) of the motorcycle. (ii) Find the speed (v) of the motorcycle at the instant it overtakes the car. (b) Sketch of the position of the car and that of the motorcycle as functions of time is shown, t2 indicate the time at which car and motorcycle are travelling at the same speed. Find  and t2. [2+2+2+2] Ans: (a) (i) a = (ii) v = (b) __= t_2 _=