Askphysics Q&A - Recent questions and answers in Mechanics
http://www.askphysics.com/qa/?qa=qa/mechanics
Powered by Question2AnswerVector A + Vector B = vector C and A +2B is perpendicular to A then find relation between vector B and C.
http://www.askphysics.com/qa/?qa=466/vector-vector-vector-perpendicular-relation-between-vector
Mechanicshttp://www.askphysics.com/qa/?qa=466/vector-vector-vector-perpendicular-relation-between-vectorThu, 14 Jun 2018 09:37:37 +0000Four masses each of 4kg are fastened together.
http://www.askphysics.com/qa/?qa=460/four-masses-each-of-4kg-are-fastened-together
four masses are fastened together with four strings of 60cm each so as to form a square. This square rotates in a horizontal plane at the rate of 1 revolution in 3.14 seconds. find the tension in string.Mechanicshttp://www.askphysics.com/qa/?qa=460/four-masses-each-of-4kg-are-fastened-togetherFri, 18 May 2018 06:47:58 +0000Finding power as a function of time in transferring water from a cylinder to a container above it. Details given
http://www.askphysics.com/qa/?qa=446/finding-function-transferring-cylinder-container-details
A completely filled cylindrical tank of height H contains water of mass M. At a height h above the top of the tank there is another wide container. The entire water from the tank is to be transferred into the container in time T such that level of water in tank decreases at a uniform rate. How will the power of the external agent vary with time.Mechanicshttp://www.askphysics.com/qa/?qa=446/finding-function-transferring-cylinder-container-detailsSun, 25 Mar 2018 13:11:45 +0000Plz answer this qiestion fast
http://www.askphysics.com/qa/?qa=442/plz-answer-this-qiestion-fast
a string breaks under a load of 4.8 kg. A mass if 0.5 kg is attached to one end of the string 2m long and is rotated in a horizontal circle. calculate the greatest no of revolutions that the mass can make without breaking the stringMechanicshttp://www.askphysics.com/qa/?qa=442/plz-answer-this-qiestion-fastTue, 20 Mar 2018 00:20:03 +0000If on increasing the speed of a vehicle by 2m/s, the kinetic energy gets doubled, then what would be its initial speed?
http://www.askphysics.com/qa/?qa=439/increasing-speed-vehicle-kinetic-energy-doubled-would-initial
Mechanicshttp://www.askphysics.com/qa/?qa=439/increasing-speed-vehicle-kinetic-energy-doubled-would-initialSat, 17 Mar 2018 06:57:53 +0000Plzz solve it
http://www.askphysics.com/qa/?qa=415/plzz-solve-it
Two particles of mass 3kg & 5kg are placed 6m apart.Heavier mass is moved away from lighter mass by 3m .How much should 3kg mass be moved so that CENTRE OF MASS of system shifts towards 3kg by 25 cmMechanicshttp://www.askphysics.com/qa/?qa=415/plzz-solve-itSat, 06 Jan 2018 10:42:06 +0000The linear mass of density of a ladder of length l increases uniformly from one end A to the other end B
http://www.askphysics.com/qa/?qa=380/linear-density-ladder-length-increases-uniformly-from-other
The linear mass of density of a ladder of length l increases uniformly from one end A to the other end B.(a) Form an expression for the linear mass density as a function of distance x from end A where linear mass density d. The density at one end being twice that of the other end.(b) Find the position of the centre of mass from end A.Mechanicshttp://www.askphysics.com/qa/?qa=380/linear-density-ladder-length-increases-uniformly-from-otherFri, 27 Oct 2017 08:09:18 +0000For a pendulum of mass m displaced by 30° the tension is t=mgcos30° but why can't I resolve tension and get tcos30°= mg?
http://www.askphysics.com/qa/?qa=379/pendulum-displaced-tension-mgcos30%C2%B0-resolve-tension-tcos30%C2%B0
Mechanicshttp://www.askphysics.com/qa/?qa=379/pendulum-displaced-tension-mgcos30%C2%B0-resolve-tension-tcos30%C2%B0Thu, 26 Oct 2017 17:10:42 +0000A uniform rod AB is bent in the shape of an arc of the circle. Determine angular acceleration
http://www.askphysics.com/qa/?qa=372/uniform-bent-shape-circle-determine-angular-acceleration
See here : figure for this question <a href="https://issuu.com/osanoothu/docs/doc-116-b.p.s.-xi-physics-iit-jee-a/77.ans" rel="nofollow" target="_blank">https://issuu.com/osanoothu/docs/doc-116-b.p.s.-xi-physics-iit-jee-a/77.ans</a> the second part also which we have to show alsoMechanicshttp://www.askphysics.com/qa/?qa=372/uniform-bent-shape-circle-determine-angular-accelerationWed, 18 Oct 2017 18:06:33 +0000http://i.imgur.com/OnLYz2q.jpg . Can anyone pls try to solve the second part of question.
http://www.askphysics.com/qa/?qa=371/http-imgur-onlyz2q-anyone-pls-solve-the-second-part-question
Mechanicshttp://www.askphysics.com/qa/?qa=371/http-imgur-onlyz2q-anyone-pls-solve-the-second-part-questionWed, 18 Oct 2017 18:00:21 +0000Work done by kinetic friction on a block modelled as a system
http://www.askphysics.com/qa/?qa=342/work-done-by-kinetic-friction-on-a-block-modelled-as-a-system
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Let's consider a setup consisting of a table with friction, and a block on top of it. Suppose we drag the block across the table with a constant speed. The applied force F acting through a distance ddoes a work Fd. The frictional force is equal to -F since there is no acceleration. So the total work done on the block by these external forces will be W_{app} + W_{friction} = F_{app}d - f_{Kinetic Friction}d = 0.</div>
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According to law of conservation of energy, if there is an energy change in the system , it is because the energy is being transferred across the system boundary by a transfer mechanism (work, heat, mechanical waves, matter transfer, electromagnetic radiation etc.) </div>
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So, Delta E_{system} = Sigma T, where Delta E_{system} = Delta K + Delta U + Delta E_{internal} and Sigma T is an energy transfer mechanism.</div>
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In our case, we have W_{app} + W_{friction} = Delta K + Delta E_{internal} , Delta K = 0 as there is no change in speed, then W_{app} + W_{friction} = Delta E_{internal} , but as W_{app} + W_{friction} = 0 that means delta E_{internal} = 0 So that means there is no increase in the internal energy, but clearly the block heats up. Can anyone explain to me what's happening here? Why is law of conservation of energy being violated? And also I tried to use Latex so the equations would appear as math symbols but apparently it doesn't work here.</div>Mechanicshttp://www.askphysics.com/qa/?qa=342/work-done-by-kinetic-friction-on-a-block-modelled-as-a-systemTue, 19 Sep 2017 11:15:21 +0000Answered: Question on vectors.
http://www.askphysics.com/qa/?qa=257/question-on-vectors&show=318#a318
Given vector is R = 10i + 10j <br />
Consider is sum of two small vectors say a= 10i and b=10j <br />
Then componenting vector a in the new frame of reference we get <br />
10 cos 30° along i and 10sin 30° Along j. Similarly componenting vector b we get <br />
10 cos 30° along j and 10 sin 30°along i. <br />
Therefore, <br />
new a= {(10 root 3)/2} i - {10/2} j<br />
new b= {10/2} i +{(10 root 3) /2} j<br />
So, new R = new a + new b<br />
={(10/2) + (10 root 3)/2} i + {(10 root 3)/2 - (10/2)}j<br />
= 5(1 + root 3) i + 5 (root 3 - 1) j<br />
= 5 x 2.73 i + 5 x 0.73 j<br />
=13.65i +3.65jMechanicshttp://www.askphysics.com/qa/?qa=257/question-on-vectors&show=318#a318Tue, 19 Sep 2017 05:43:29 +0000Answered: Action -reaction-potential energy
http://www.askphysics.com/qa/?qa=104/action-reaction-potential-energy&show=312#a312
Mg is downward force and if upward force equal to mg is applied then both the forces cancel out each other and net force on the body is zero. That is net acceleration of the body is zero. But it doesn't mean velocity is zero. The body will move with constant velocity. Hence, body moves.Mechanicshttp://www.askphysics.com/qa/?qa=104/action-reaction-potential-energy&show=312#a312Wed, 13 Sep 2017 06:04:06 +0000Answered: Problem related to mechanics
http://www.askphysics.com/qa/?qa=267/problem-related-to-mechanics&show=306#a306
Just use concept of relative velocity and vectors to solve this problem. Easy enough.Mechanicshttp://www.askphysics.com/qa/?qa=267/problem-related-to-mechanics&show=306#a306Wed, 13 Sep 2017 05:36:45 +0000Answered: Can I roll a spehre with out friction acting on it? (Not a frictionless surface)What about the front car wheel?
http://www.askphysics.com/qa/?qa=141/spehre-friction-acting-frictionless-surface-about-front-wheel&show=298#a298
Zero never exist. It's ideal imagination and nothing else. One can minimize it to practically negligible value but not zero.<br />
Applicable if you are dealing with physical body.Mechanicshttp://www.askphysics.com/qa/?qa=141/spehre-friction-acting-frictionless-surface-about-front-wheel&show=298#a298Tue, 12 Sep 2017 14:41:56 +0000Answered: Can a cyclist pedal during free fall? Cyclist's waist is tied to the seat.
http://www.askphysics.com/qa/?qa=201/can-cyclist-pedal-during-free-fall-cyclists-waist-tied-seat&show=297#a297
Obviously he /she can pedal. There's nothing that can stop him from pedaling while free fall. Anything that involves weight will be affected surely but pedaling has nothing to do with pedaling.Mechanicshttp://www.askphysics.com/qa/?qa=201/can-cyclist-pedal-during-free-fall-cyclists-waist-tied-seat&show=297#a297Tue, 12 Sep 2017 14:39:58 +0000Answered: What is the percentage change in period of simple pendulum if angular amplitude is increased to 60 degree?
http://www.askphysics.com/qa/?qa=190/percentage-simple-pendulum-angular-amplitude-increased-degree&show=295#a295
You can use formula given in units and measurements of ncert 11th physics. <br />
Time period T= 2(pi) (L /g) ^(1/2)<br />
Hence, <br />
(Delta T/ T) = (1/2) (delta L/ L)Mechanicshttp://www.askphysics.com/qa/?qa=190/percentage-simple-pendulum-angular-amplitude-increased-degree&show=295#a295Tue, 12 Sep 2017 14:33:50 +0000Answered: Why does not the mass of whole earth is taken,during calculating the 'g' at depth?
http://www.askphysics.com/qa/?qa=121/does-not-mass-whole-earth-taken-during-calculating-the-depth&show=291#a291
While calculating g at depth whole mass of earth is not considered because at that depth body don't experience any attractive force due to outer mass of earth. The gravitational force experienced is only and only due to the mass enclosed by inner circle.Mechanicshttp://www.askphysics.com/qa/?qa=121/does-not-mass-whole-earth-taken-during-calculating-the-depth&show=291#a291Tue, 12 Sep 2017 10:42:25 +0000Answered: what is the mass flow rate in (kg/s) of water from the vessel?
http://www.askphysics.com/qa/?qa=119/what-is-the-mass-flow-rate-in-kg-s-of-water-from-the-vessel&show=290#a290
I assume container is filled full. Then volume of water flowing per second = (5700 m^3) / (12 x 60s) <br />
=7.92 m^3 per s <br />
And given density of water is 1g per cm^3 i.e. 1000kg per m^3.<br />
Hence mass flowing per second is = (1000 kg m^-3) x (7.92 m^3 /s) <br />
=7920 kg /sMechanicshttp://www.askphysics.com/qa/?qa=119/what-is-the-mass-flow-rate-in-kg-s-of-water-from-the-vessel&show=290#a290Tue, 12 Sep 2017 10:36:48 +0000how to calculate branch flow rate in dividing manifold?
http://www.askphysics.com/qa/?qa=269/how-to-calculate-branch-flow-rate-in-dividing-manifold
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in the spirit of keeping it direct i will jump right to the question. How can I calculate the flow rate at the entrance of pipe branches in a divider manifold? I am building this model solar panel and along side it i am building a thermal model and i need to know in the flow in at each pipe to calculate the rest. </div>
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Thanks for your help in advance</div>Mechanicshttp://www.askphysics.com/qa/?qa=269/how-to-calculate-branch-flow-rate-in-dividing-manifoldWed, 16 Aug 2017 13:44:14 +0000what is vector resolution
http://www.askphysics.com/qa/?qa=170/what-is-vector-resolution
what is vector resolution how can i resolve a vector into its components in terms of sin and cosMechanicshttp://www.askphysics.com/qa/?qa=170/what-is-vector-resolutionSun, 04 Jan 2015 11:36:31 +0000Answered: for uniform motion ,whether velocity is independent of origin or not
http://www.askphysics.com/qa/?qa=114/for-uniform-motion-whether-velocity-independent-origin-not&show=149#a149
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For uniform motion, </p>
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Slope = dx/dt= displacement/time</div>
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Velocity (V) =dx/ dt, is constant ,</div>
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so its independent of orgin .</div>
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</div>Mechanicshttp://www.askphysics.com/qa/?qa=114/for-uniform-motion-whether-velocity-independent-origin-not&show=149#a149Sat, 06 Dec 2014 21:19:11 +0000Answered: maruti800 to electric car
http://www.askphysics.com/qa/?qa=124/maruti800-to-electric-car&show=126#a126
Sir, <br />
I don't know exact specification about motor type but I can tell you that electric car requires battery. Highest efficiency achieved by normal acid cell battery is 25 watt per kilo. To run the car up to a practical distance the battery alone will cost you near 1 lakh not to mention that the car will be dead heavy. A lithium ion battery can have a electricity of 100 watt per kilo so vehicle will be lighter but then again price of that much big Barry will be more than a new maruti 800Mechanicshttp://www.askphysics.com/qa/?qa=124/maruti800-to-electric-car&show=126#a126Tue, 18 Nov 2014 22:10:55 +0000Hello everybody.I have a question in kinematics
http://www.askphysics.com/qa/?qa=120/hello-everybody-i-have-a-question-in-kinematics
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Hello everybody.I have a question in kinematics.</div>
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A vehicle wants to move on the perimeter of (around) an imaginary ellipse at 60 km/h.Determine the range of "a" and "b" in order that the Normal component(perpendicular) of acceleration does'nt exceed than 10.5 m/s^2.take a look at photo please.Hello everybody. ## x^2/a^2 + y^2/b^2 = 1 ##<img alt="" src="http://www.askphysics.com/qa/?qa=blob&qa_blobid=6407012005818900336" style="width: 363px; height: 256px;"></div>Mechanicshttp://www.askphysics.com/qa/?qa=120/hello-everybody-i-have-a-question-in-kinematicsWed, 05 Nov 2014 17:08:01 +0000what is the mass flow rate in (kg/s) of water from the vessel
http://www.askphysics.com/qa/?qa=118/what-is-the-mass-flow-rate-in-kg-s-of-water-from-the-vessel
the capacity of a vessel is 5700mcube the vessel is filled with water.suppose that it takes 12 hours to drain the vessel what is the mass flow rate in kg/s of water from the vessel?the density of water is 1g/cmcube?Mechanicshttp://www.askphysics.com/qa/?qa=118/what-is-the-mass-flow-rate-in-kg-s-of-water-from-the-vesselThu, 23 Oct 2014 17:13:19 +0000Answered: we know that a particle cannot travel distance at particular instance but how instantaneous speed exist?
http://www.askphysics.com/qa/?qa=94/particle-cannot-distance-particular-instance-instantaneous&show=106#a106
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<span style="font-size:14px;">Instantaneous speed means speed at a particular instance not the distance travelled in that instant of time.</span>If a</p>
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body is accelerating its velocity is continuosly increasing?yes/no??</p>
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So,it will possess a instantaneous velocity(same applies if a body is moving with a constant velocity)...</p>
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Ex:Watch the speedometer of a 2 or 4 wheeler.</p>
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@Gopikrishna Mogasati</p>Mechanicshttp://www.askphysics.com/qa/?qa=94/particle-cannot-distance-particular-instance-instantaneous&show=106#a106Mon, 01 Sep 2014 16:37:01 +0000Answered: dt tends to 0 then ds tends to 0 but how it is possible that ds/dt do not go towards 0/0 but attain finite value v
http://www.askphysics.com/qa/?qa=95/tends-then-tends-possible-that-towards-attain-finite-value&show=105#a105
The values of differentiation (ratioie..,v=ds/dt) as viewed in graph perspective(displacement vs time) is a super super fine approximation value.ie..,we are not having a math or physical tool to exactly find the velocity at a particular point if a body is accelearting as time progresses.<br />
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First question yourself how erraneous your distance calculation is??considering exact physical happening with your naked eye can you find by viewing with your eye how much distance a car accelarating at 10m/sq.sec has travelled in millimicron second and keep pencil on the graph sheet pin pointedly that value.ie,,. we humans are limited to comprehend and express physics exactly.even we don't have a super fine sharped pencil to point a value exactly.<br />
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So,what we have done is to approximate calculation as nearer to the original exact value,and also we have to be aware of that no object can change its velocity value without a small 0.00000000..........1(can't comprehend how small it can be)time gap.The proof is if a body is accelerating it cannot have same value in suucessive intervals of time.<br />
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So in taking the ratio(ds/dt) we are more are less limiting to this time interval!!!!!.Also remember that a larger number of small lines can fit into a curve (I mean graph).It is the length of this line(depending on the graph shape) that determines the small time value.<br />
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We do not make ds--->0(tending to zero) ,only dt--->0(tending to zero) to ease the math calculations!!!!!<br />
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After all math stuff in some topics aims to how close we are to physics but not viceversa.<br />
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Hope this clarifies,<br />
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Thanks@Gopikrishna Mogasati.Mechanicshttp://www.askphysics.com/qa/?qa=95/tends-then-tends-possible-that-towards-attain-finite-value&show=105#a105Sun, 31 Aug 2014 16:57:13 +0000find the time after which the block A collides with the block B?
http://www.askphysics.com/qa/?qa=71/find-the-time-after-which-the-block-collides-with-the-block-b
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A plank of mass 10 kg rests on a smooth horizontal surface. 2 blocks A and B of masses 2 kg and 1 kg respectively lies at a distance of 3 m from each other on a large plank . the friction coefficient between block A and plank is 0.3 and between block B and plank is 0.1 . friction coefficient between ground and plank is zero. now a force of 15 N is applied on the plank in horizontal direction. find the time after which the block A collides with the block B?</div>
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how to solve it???</div>
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the answer is 6 seconds...</div>Mechanicshttp://www.askphysics.com/qa/?qa=71/find-the-time-after-which-the-block-collides-with-the-block-bThu, 17 Jul 2014 07:44:49 +0000Answered: What is the difference between a pulse and a wave?
http://www.askphysics.com/qa/?qa=41/what-is-the-difference-between-a-pulse-and-a-wave&show=45#a45
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PULSE IS A WAVE OF SHORT DURATION</p>
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<b style="color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;">pulse</b><span style="color: rgb(37, 37, 37); font-family: sans-serif; font-size: 14px; line-height: 22.399999618530273px;"> is a single disturbance that moves through a medium from one point to the next point.</span></p>
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<a href="http://en.wikipedia.org/wiki/Pulse_" rel="nofollow" target="_blank">http://en.wikipedia.org/wiki/Pulse_</a>(physics)</p>Mechanicshttp://www.askphysics.com/qa/?qa=41/what-is-the-difference-between-a-pulse-and-a-wave&show=45#a45Thu, 05 Jun 2014 17:52:42 +0000