SSC CGL परीक्षा के लिए भौतिकी क्विज 22 जनवरी 2020 : ध्वनि और गति

Q1. हवा में ध्वनि के वेग से अधिक की गति के साथ यात्रा करने वाले निकाय किस गति से यात्रा करेगा?
(a) सुपरसोनिक गति
(b) हाइपरसोनिक गति
(c) अल्ट्रासोनिक गति
(d) इन्फ्रासोनिक गति

Q2. पृथ्वी की परिक्रमा करने वाला एक कृत्रिम उपग्रह नीचे नहीं गिरता है क्यूंकि पृथ्वी का आकर्षण
(a) चंद्रमा के आकर्षण से संतुलित है
(b) ऐसी दूरी पर गायब हो जाता है
(c) वायुमंडल द्वारा उत्पादित विस्कस खिंचाव द्वारा संतुलित किया जाता है
(d) एक घुमावदार रास्ते में अपनी गति का आवश्यक त्वरण पैदा करता है

Q3. एक लम्बी कूद में व्यक्ति, कूदने से पहले दौड़ता है क्योंकि वह
(a) अधिकतम दूरी तय करता है
(b) संवेग संरक्षण बनाये रखता है
(c) दौड़ने से ऊर्जा प्राप्त करता है
(d) संवेग प्राप्त करता है

Q4. एक वस्तु को लंबवत ऊपर की ओर फैकी जाती है और फिर वह जमीन पर गिरती है। इसकी संभावित स्थितिज ऊर्जा अधिकतम कहाँ होगी?
(a) जमीन पर
(b) अधिकतम ऊँचाई पर
(c) वापिस आते समय
(d) जमीन और अधिकतम ऊँचाई दोनों पर

Q5. एक जेट इंजन _______ के संरक्षण के सिद्धांत पर कार्य करता है
(a) रेखीय संवेग
(b) कोणीय संवेग
(c) ऊर्जा
(d) द्रव्यमान

Q6. किसी व्यक्ति को लिफ्ट में भारीपन कब महसूस होता है?
(a) तेजी से नीचे की ओर जाती है
(b) ऊपर जाना आरम्भ होती है
(c) तेजी से ऊपर बढ़ती है
(d) नीचे की ओर आती है

Q7. एक हवाई जहाज की लिफ्ट _______पर आधारित है
(a) टोरिसेली का प्रमेय
(b) बरनौली का प्रमेय
(c) गुरुत्वाकर्षण का नियम
(d) रैखिक संवेग का संरक्षण

Q8. वाशिंग मशीन किस नियम पर कार्य करती है?
(a) केन्द्रापसारण
(b) डायलिसिस
(c) रिवर्स ऑस्मोसिस
(d) विसरण

Q9. एक निकाय के संवेग के परिवर्तन की दर परिणामी _________ के बराबर है:
(a) ऊर्जा
(b) शक्ति
(c) बल
(d) आवेग

Q10. ध्वनि की तीव्रता की SI इकाई क्या है?
(a) डेसिबल
(b) न्यूटन
(c) हर्ट्ज
(d) टेस्ला

Solutions

S1. 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.

S2. 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 be great enough so gravity brings the satellite back to Earth but not so great that the satellite escapes gravity out into space.

S3. Ans.(b)
Sol. A long jumper runs before jumping to maintain momentum. This helps in jumping higher and longer because of inertia of motion gained due to the motion.

S4. Ans.(b)
Sol. We know that
Potential energy = mgh
Hence potential energy is maximum at the maximum height.

S5. Ans.(a)
Sol. A jet engine works on the principle of conservation of linear momentum. In jet engines, a large volume of gases produced by the combustion of fuel is allowed to escape through a jet in the backward direction. Due to the very high speed or velocity, the backward rushing gases have a very large momentum.

S6. Ans.(b)
Sol. One feels heavier in a lift when the lift just begins to go up because our body gains inertia from the position of rest and pushes up against the gravity so here the weight becomes zero and our mass makes us feel heavier.

S7. Ans.(b)
Sol. Bernoulli’s theorem which says that if air speeds up the pressure is lowered. Thus a wing generates lift because the air goes faster over the top creating a region of low pressure, and thus lift.

S8. Ans.(a)
Sol. Washing machine works on the principle of centrifugation. Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures with a centrifuge, used in industry and in laboratory settings. More-dense components of the mixture migrate away from the axis of the centrifuge, while less-dense components of the mixture migrate towards the exis.

S9. Ans.(c)
Sol. The rate of change of momentum of an object is directly proportional to the resultant force applied and is in the direction of the resultant force.
S10. Ans.(a)
Sol. Decibel(dB) is the SI unit of intensity of sound.

Solutions

S1. 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.

S2. 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 be great enough so gravity brings the satellite back to Earth but not so great that the satellite escapes gravity out into space.

S3. Ans.(b)
Sol. A long jumper runs before jumping to maintain momentum. This helps in jumping higher and longer because of inertia of motion gained due to the motion.

S4. Ans.(b)
Sol. We know that
Potential energy = mgh
Hence potential energy is maximum at the maximum height.

S5. Ans.(a)
Sol. A jet engine works on the principle of conservation of linear momentum. In jet engines, a large volume of gases produced by the combustion of fuel is allowed to escape through a jet in the backward direction. Due to the very high speed or velocity, the backward rushing gases have a very large momentum.

S6. Ans.(b)
Sol. One feels heavier in a lift when the lift just begins to go up because our body gains inertia from the position of rest and pushes up against the gravity so here the weight becomes zero and our mass makes us feel heavier.

S7. Ans.(b)
Sol. Bernoulli’s theorem which says that if air speeds up the pressure is lowered. Thus a wing generates lift because the air goes faster over the top creating a region of low pressure, and thus lift.

S8. Ans.(a)
Sol. Washing machine works on the principle of centrifugation. Centrifugation is a process that involves the use of the centrifugal force for the separation of mixtures with a centrifuge, used in industry and in laboratory settings. More-dense components of the mixture migrate away from the axis of the centrifuge, while less-dense components of the mixture migrate towards the exis.

S9. Ans.(c)
Sol. The rate of change of momentum of an object is directly proportional to the resultant force applied and is in the direction of the resultant force.

S10. Ans.(a)
Sol. Decibel(dB) is the SI unit of intensity of sound.

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