# Physics Quiz For ALP Stage-II Quiz Exam : 29th December 2018

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Q1. The time period of a pendulum depends on
एक पेंडुलम की अवधि किस पर निर्भर करती है-
(a) the mass/द्रव्यमान पर
(b) the length/लंबाई पर
(c) the time/समय पर
(d) both (a) and (b)/ दोनों (a) और (b)

Ans.(b)
Sol. Time period T = 2π√(l/g) . The time period of a pendulum depends on its length l and acceleration due to gravity g.

Q2. Which of the following is the smallest unit of length?
निम्नलिखित में से क्या लंबाई की सबसे छोटी इकाई है-
(a) Micrometre/ माइक्रोमीटर
(b) Nanometre  / नैनोमीटर
(c) Angstrom / ऐंग्स्ट्रॉम
(d) Fermimetre /फर्मीमीटर

Ans. (d)
Sol. 1 micron = 10-6 m
1 nanometer = 10-9  m
1 angstrom = 10-10  m
1 fermi = 10-15 m

Q3. A man is standing on a boat in still water. If he walks towards the shore, the boat will
एक व्यक्ति स्थिर पानी में एक नाव पर खड़ा है.  यदि वह किनारे की तरफ चलता है, तो नाव-
(a) move towards the shore/ किनारे की ओर बढ़ेंगी
(b) move away from the shore/ किनारे से दूर जाएगी
(c) remain stationary/ स्थिर रहेगी
(d) sink/डूब जाएगी

Ans.(b)
Sol. According to Newton’s third law of motion, every action has an equal and opposite reaction. This implies that force always occurs in pairs where if object a exerts a force “F” on object B, then object B exerts an equal and opposite force “—F” on object A. Thus, if a man standing on a boat in still water  begins to walk towards the shore then in response to this , the boat will start moving away from the shore.

Q4. One micron represents a length of
एक माइक्रोन कितनी लंबाई को दर्शाती है-
(a) 10^(-6) m
(b) 10^(-4) m
(c) 10^(-3) m
(d) 1 m

Ans (a)
Sol.  One micron represents a length of 10 -6 m While milli represents 10-3 m.

Q5. A body travelling with a speed of more than the velocity of sound in air is said to travel with
हवा में ध्वनि के वेग से अधिक की गति के साथ यात्रा करने वाले निकाय किस गति से यात्रा करेग
(a) supersonic speed/ सुपरसोनिक गति
(b) hypersonic speed/ हाइपरसोनिक गति
(c) ultrasonic speed/ अल्ट्रासोनिक गति
(d) infrasonic speed/इन्फ्रासोनिक गति

Ans (a)
Sol. Supersonic speed is a rate of travel of an object that exceeds the speed of sound. For objects travelling  in dry air of a temperature of 20°C at sea level, this speed is approximately 343 m/s.

Q6. A passenger in a moving train tosses a coin. If the coin falls behind him, the train must be moving with
चलती ट्रेन में एक यात्री एक सिक्का उछालता है। अगर सिक्का उसके पीछे गिरता है, तो ट्रेन ¬¬_______ के साथ चल रही है.
(a) an acceleration / त्वरण
(b) a deceleration/ अवत्‍वरण
(c) a uniform speed/ समान गति
(d) any of the above/ उपर्युक्त में से कोई

Ans(a)
Sol.  If the train were moving with uniform velocity, the coin would fall back to the passenger’s hand. While, if the train is accelerated, the horizontal velocity of the train would be more than that of the coin by the time the coin returns. Therefore, the train travels a greater horizontal distance than the coin and coin falls behind the passenger.

Q7. China wares are wrapped in straw of paper before packing. This is the application of concept of
चीन के माल पैकिंग से पहले कागज के पुआल में लिपटे हुए होते हैं। यह अवधारणा किस का अनुप्रयोग है
(a) impulse/ आवेग
(b) momentum/ गति
(c) acceleration / त्वरण
(d) force/ बल
Ans (a)
Sol. As a certain impulse applied for a short time will give a large force so the chinaware breaks into pieces. Therefore, chinaware is wrapped in straw of paper while packing so that the event of fall (impact) will take a longer time to reach the chinaware through straw of paper and hence the average force exerted on the chinaware is small and chances of its breaking reduce.

Q8. When a body is stationary, then
जब कोई शरीर स्थिर होता है, तब
(a) there is no force acting on it/ इस पर कोई बल नहीं है
(b) the body is in vacuum/ निकाय निर्वात में है
(c) the force acting on it is not in contact with it/ इस पर कार्य करने वाला बल इसके संपर्क में नहीं है
(d) the net forces acting on it balances each other/ इस पर कार्य करने वाला बल एक दूसरे को संतुलित करता हैं
Ans (d)
Sol. For both stationary and moving objects with unchanging speed and direction, all the forces acting on the objects are in balance with each other, i.e. they all cancel each other.

Q9. What happens when a heavy object and a light object are allowed to fall from the certain height in the absence of air
जब एक भारी वस्तु और एक हल्की वस्तु को हवा की अनुपस्थिति में निश्चित ऊंचाई से गिरती है टैब क्या होता है?
(a) heavy object reaches the ground later than the lighter object/भरी वस्तु हलकी वस्तु की तुलना में ज़मीन पर बाद में पहुंचता है
(b) lighter object reaches the ground later than the heavier object /हलकी वस्तु भरी वस्तु की तुलना में ज़मीन पर बाद में पहुँचता है
(c) both heavy and light objects reach the ground simultaneously / भारी और हल्की दोनों वस्तुएं एक साथ जमीन पर पहुंचती हैं
(d) None of these/इनमें से कोई नहीं
Ans (c)
Sol. If no air resistance is present, the rate of descent depends only on how far the object has fallen, no matter how heavy the object is. This means that two objects will reach the ground at the same time if they are dropped simultaneously from the same height.
This statement follows from the law of conservation of energy. However, if air resistance is present, then the shape of the object becomes important.

Q10. An artificial satellite orbiting the earth does not fall down because the earth’s attraction
पृथ्वी की परिक्रमा करने वाला एक कृत्रिम उपग्रह नीचे नहीं गिरता है क्यूंकि पृथ्वी का आकर्षण
(a) is balanced by the attraction of the moon/ चंद्रमा के आकर्षण से संतुलित है
(b) vanishes at such distances/ ऐसी दूरी पर गायब हो जाता है
(c) is balanced by the viscous drag produced by the atmosphere/ वायुमंडल द्वारा उत्पादित विस्कस खिंचाव द्वारा संतुलित किया जाता है
(d) produces the necessary acceleration of its motion in a curved path/ एक घुमावदार रास्ते में अपनी गति का आवश्यक त्वरण पैदा करता है
Ans (d)

Sol. An artificial satellite orbiting around the Earth does not fall down. This is so because the attraction of earth provides the necessary acceleration for its motion. This acceleration is “constant” in magnitude but “changing in direction”. By the launch rocket, immediately before the satellite is established in the predetermined orbit, the speed given to it is 30,000 km/hr. The speed must be great enough so gravity brings the satellite back to Earth but not so great that the satellite escapes gravity out into space.

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