Convergence P H Y S I C S

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Shawn Smith
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1 +1 Test (Newton s Law of Motion) 1. Inertia is that property of a body by virtue of which the body is (a) Unabe to change by itsef the state of rest (b) Unabe to change by itsef the state of unifor otion Unabe to change by itsef the direction of otion (d) Unabe to change by itsef the state of rest and of unifor inear otion. A person sitting in an open car oving at constant veocity throws a ba verticay up into air. The ba fas (a) Outside the car (b) In the car ahead of the person In the car to the side of the person (d) Exacty in the hand which threw it up 3. If a buet of ass 5 g oving with veocity 100 /sec, penetrates the wooden bock upto 6 c. Then the average force iposed by the buet on the bock is (a) 8300 N 830 N (b) 17 N (d) Zero. A diwai rocket is ejecting 0.05 kg of gases per second at a veocity of 00 /sec. The acceerating force on the rocket is (a) 0 dynes dynes (b) 0 N (d) 1000 N 5. A body of ass kg is hung on a spring baance ounted verticay in a ift. If the ift descends with an acceeration equa to the acceeration due to gravity g, the reading on the spring baance wi be (a) kg (b) ( g) kg ( g) kg (d) Zero 6. In doubing the ass and acceeration of the ass, the force acting on the ass with respect to the previous vaue (a) Decreases to haf (b) Reains unchanged Increases two ties (d) Increases four ties 7. A achine gun is ounted on a 000 kg car on a horizonta frictioness surface. At soe instant the gun fires buets of ass 10 g with a veocity of 500 /sec with respect to the car. The nuber of buets fired per second is ten. The average thrust on the syste is (a) 550 N 50 N (b) 50 N (d) 50 dyne 8. A person is standing in an eevator. In which situation he finds his weight ess than actua when (a) The eevator oves upward with constant acceeration (b) The eevator oves downward with constant acceeration. The eevator oves upward with unifor veocity (d) The eevator oves downward with unifor veocity 9. A bock of eta weighing kg is resting on a frictioness pane. It is struck by a jet reeasing water at a rate of 1 kg/sec and at a speed of 5 /sec. The initia acceeration of the bock wi be (a).5 / sec (b) 5.0 / sec 10 / sec

2 (d) None of the above 10. At a pace where the acceeration due to gravity is 10 sec a force of 5 kg-wt acts on a body of ass 10 kg initiay at rest. The veocity of the body after second is (a) 5 sec (b) 10 sec 0 sec (d) 50 sec A rocket has an initia ass of 0 0 kg. If it is to bast off with an initia acceeration of s, the initia thrust needed is ~ ( g 10s ) (a) 6 10 N (b) 8 10 N 0 10 N (d) 1 10 N 1. A force vector appied on a ass is represented as F 6ˆi 8ˆj 0kˆ and acceerates with 1 / s. What wi be the (a = acceeration of ift) (a) g (b) ( g a) ( g a) (d) 0 1. A pub ine is suspended fro a ceiing of a car oving with horizonta acceeration of a. What wi be the ange of incination with vertica (a) tan 1 ( a / g) (b) tan 1 ( g / a ) cos 1 ( a / g) (d) cos 1 ( g / a ) 15. The inear oentu p of a body oving in one diension varies with tie according to the equation p a bt where a and b are positive constants. The net force acting on the body is (a) A constant (b) Proportiona to t Inversey proportiona to t (d) Proportiona to t 16. A an is standing on a baance and his weight is easured. If he takes a step in the eft side, then weight (a) Wi decrease (b) Wi increase Reains sae (d) First decreases then increases 17. Action and reaction forces act on (a) The sae body (b) The different bodies The horizonta surface (d)nothing can be said 18. A cycist turns around a curve at 15 ass of the body ies/hour. If he turns at doube the (a) 10 kg (b) 10 kg speed, the tendency to overturn is 10 kg (d) 0 kg (a) Doubed (b) Quadruped 13. If rope of ift breaks suddeny, the Haved (d) Unchanged tension exerted by the surface of ift 19. A cycist [AFMC taking 00] turn bends inwards whie a car passenger taking sae turn is thrown outwards. The reason is (a) Car is heavier than cyce (b) Car has four whees whie cyce has ony two Difference in the speed of the two (d)cycist has to counteract the centrifuga force whie in the case of car ony the passenger is thrown by this force 0. Two asses M and are attached to a vertica axis by weightess threads of cobined ength. They are set in rotationa otion in a horizonta pane about this axis with constant anguar veocity. If the tensions in the threads

3 are the sae during otion, the distance of M fro the axis is (a) M M M M (b) (d) M M 1. A sphere of ass is tied to end of a string of ength and rotated through the other end aong a horizonta circuar path with speed v. The work done in fu horizonta circe is v (a) 0 (b). v g. (d).( ). The anguar speed of seconds neede in a echanica watch is (a) rad/s (b) rad/s 30 rad/s (d) 60 rad/s 3. The anguar veocity of a whee is 70 rad/sec. If the radius of the whee is 0.5, then inear veocity of the whee is (a) 70 /s (b) 35 /s 30 /s (d) 0 /s. A cycist riding the bicyce at a speed of 1 3 s 1 takes a turn around a circuar road of radius 0 3 without skidding. Given g = 9.8 s, what is his incination to the vertica (a) 30 o (b) 90 o 5 o (d) 60 o 5. A proton of ass kg goes round in a circuar orbit of radius 0.10 under a centripeta force of N. then the frequency of revoution of the proton is about (a) cyces per sec (b) 10 8 cyces per sec cyces per sec (d) cyces per sec Reason and Assertion Read the assertion and reason carefuy to ark the correct option out of the options given beow: (a) (b) (d) (e) If both assertion and reason are true and the reason is the correct expanation of the assertion. If both assertion and reason are true but reason is not the correct expanation of the assertion. If assertion is true but reason is fase. If the assertion and reason both are fase. If assertion is fase but reason is true. 6. Assertion : Force is required to ove a body unifory aong a circe. Reason : When the otion is unifor, acceeration is zero. 7. Assertion : If two objects of different asses have sae oentu, the ighter body possess greater veocity. Reason : For a bodies oentu aways reains sae. 8. Assertion : The sope of oentu versus tie curve give us the acceeration. Reason : Acceeration is given by the rate of change of oentu. 9. Assertion : A cycist aways bends inwards whie negotiating a curve. Reason : By bending, cycist owers his centre of gravity. 30. Assertion : When the ift oves with unifor veocity the an in the ift wi fee weightessness.

4 Reason : In downward acceerated otion of ift, apparent weight of a body decreases.

5 1 d d 3 b b 5 d 6 d 7 b 8 b 9 a 10 c 11 b 1 a 13 d 1 a 15 d 16 c 17 b 18 b 19 d 0 b 1 a a 3 b d 5 a 6 b 7 c 8 d 9 c 30 e 1. (d). (d) Horizonta veocity of ba and person are sae so both wi cover equa horizonta distance in a given interva of tie and after foowing the paraboic path the ba fas exacty in the hand which threw it up. 3. (b) u 100 / s, v 0, s Retardation u (100) 1 0 a s Force a 17 N 1 1 d dt. (b) F u N 5. (d) Reading on the spring baance = (g a) and since a = g Force = 0 6. (d) Force = Mass Acceeration. If ass and acceeration both are doubed then force wi becoe four ties. 7. (b) u = veocity of buet d Mass thrown per second by the dt achine gun = Mass of buet Nuber of buet fired per second 10 g 0 buet/ sec 100 g / sec 0.1 kg / sec 6 8. (b) Thrust ud dt N 9. (a) Force on the bock F F d u 5 5 N dt Acceeration of bock a 5.5 / s Force 50 N 5 / s Mass 10 kg 10. Acceeration 11. (b) Fro v u at / s F ( g a) 00 (10 ) 8 0 v u t 1. (a) F 1. 5 N 3 5(65 5) (d) If rope of ift breaks suddeny, acceeration becoes equa to g so that tension, T ( g g) 0 1. (a) When car oves towards right with acceeration a then due to pseudo force the pub ine wi tit in backward direction aking an ange with vertica. a Fro the figure, tan a / g tan 1 ( a / g) dp d 15. (d) F ( a bt ) bt dt dt (b) F t v 18. (b) F F v. If v becoes r doube then F (tendency to overturn) wi becoe four ties. 19. (d) 0. (b) If the both ass are revoving about the axis yy' and tension in both the threads are equa then g N a

6 M x ( x) Mx ( x) x M 1. (a) Work done by centripeta force in unifor circuar otion is aways equa to zero.. (a) rad/ s T (b) v r / s. (d) tan 60 v tan rg 3 5. (a) n r 0 (1 3) tan n cyces / sec. 6. (b) When a body is oving in a circe, its speed reains sae but veocity changes due to change in the direction of otion of body. According to first aw of otion, force is required to change the state of a body. As in circuar otion the direction of veocity of body is changing so the acceeration cannot be zero. But for a unifor otion acceeration is zero (for rectiinear otion). 7. According to definition of oentu P v if P = constant then v = constant or 1 v. As veocity is inversey proportiona to ass, therefore ighter body possess greater veocity. dp 8. (d) F Sope of oentu-tie dt graph M x y y' [ 3] i.e. Rate of change of oentu = Sope of oentu- tie graph = force. 9. The purpose of bending is to acquire centripeta force for circuar otion. By doing so coponent of nora reaction wi counter baance the centrifuga force. 30. (e) For unifor otion apparent weight = Actua weight For downward acceerated otion, Apparent weight < Actua weight

OSCILLATIONS. dt x = (1) Where = k m

OSCILLATIONS. dt x = (1) Where = k m OSCILLATIONS Periodic Motion. Any otion, which repeats itsef at reguar interva of tie, is caed a periodic otion. Eg: 1) Rotation of earth around sun. 2) Vibrations of a sipe penduu. 3) Rotation of eectron