If you had a metal plate with a hole in its center, and uniformly heated it for a finite time, what will happen to the diameter of the hole?
Diameter of hole will increase.This is a classic question. Many of us "expect" that diameter of hole will decrease, because plate is free to expand in that direction as well. Note that expansion of metal due to heating is not like gas spreading out wherever space is available.Correct way to think about it is following. Hole size is irrelevant in this case. So we can think that hole is very large. If we carve hole so large such that it's radius is slightly less than that of plate itself, then we will have a ring. It is obvious that radius of ring will increase, as atoms have more energy so there oscillation amplitude will increase. As diameter of ring increases, diameter of hole will also increase.
How do you calculate the cross section area of cylinder?
The Cross section of an object is the shape you get when you cut straight through an object. It can be a rectangle, a circle even an oval, depending on how it has been cut.A circleThus the cross section of the above cylinder is a circle. Hence the cross sectional area is the area of a circle.Area of a circle = π x R2R= radiusA RectangleThus the cross section of the above cylinder is a rectangle, hence calculate the area of a rectangle.Area of a rectangle= length*widthAn OvalThus the cross section of the above cylinder is an oval, hence calculate the area of the oval.Area of an oval= π*short radius*long radiusUsing the figure below as an example, the short radius is a the long radius is bthus the area is = π*a*bSo what will guide you is how it has been cut. Good Day.
What is a gallaxy?What are the names of known gallaxies?
a galaxy is a group of stars, consisting of a few hundred million or more, depending on their size. our galaxy is called the milky way, and the nearest galaxy is the andromeda galaxy
A sphere, cube, circular plate all three are heated to 1000 degree. Which will cool first?
Assuming all three are made up of the same material, and the same volume of the material, the circular plate will cool first, as it has the largest surface area among the 3 given shapes. More surface area means that there is more area in contact with the atmosphere. This can be visualized too. Take your cup of coffee and measure the time it takes to come to room temperature.(Make sure there is no other variable affecting the temperature like a fan or AC). Now take the same volume of coffee and pour it in a plate. The time taken for the coffee in the plate to cool must be lesser than that of the cup.Edit: I just realised that this question was asked on the basis of CBSE/JEE syllabus. Here is the answer.The power radiated by any body is given by:P= e (sigma)(area)((Temp of body)^4-(temp of surrounding)^4)Since e(emissivity) is independent on area of the material and is purely dependent on the material and since power radiation is directly proportional to area, higher the surface area, higher is the energy emitted per second. Since the plate has the highest area of the three assuming same volume, it will radiate the most energy per second and hence will cool down the fastest.
The area of the square is 144 sq. m. What is the length of its side?
A square has four equal sides. Let x be the length of each side of the square. So, the formula for the area of a square is:Area of Square = x × x = x²Given the area of the square is 144 m². Then, we have144 = x²√144 = √x²12 = xx = 12Thus, the length of each side of the square is 12 m.
How can I calculate the weight of a mild steel bar from its length?
there are two thing you should know to calculate the weight of any bar is,Unit weight of barDiameter of barso, lets have a look How can we derive ‘UNIT WEIGHT OF STEEL’still not understood ???Derivation of UNIT WEIGHT OF STEEL FORMULA, Calculation of WEIGHT OF STEEL for varies diameter.(watch the video in the given link for better understanding)Now you you know the “Unit Weight of Steel Bar”Let’s say dia of bar is 20 mmW= (20^2)/162.2 = 2.466 kg/mSo, we need 2.466 kg of steel for 1 m length.Suppose length of bar = 6 mWeight (W) = 2.466 x 6 = 14.796 kgSubscribe to We Civil Engineers To learn a lot more stuff’s Related to CIVIL ENGINEERINGHope it helpsThank you _^_
There are 2 spheres of same material and radius. One is hollow and other is solid. If they are heated to the same temperature which expands more the solid, the hollow or they both expand the same?
Intelligent question! Hollow object contains air within, which is poor conductor of heat and can be compressed to a lesser volume. On the other hand, the other one is solid(assuming they are good conductor of heat). If uniform heat is applied to both of them at same rate, the solid one should expand slowly, as it contains more mass plus heat transfer rate between the particles are faster and to expand all the particles need to attain same K Energy at same temperature. While the hollow one contains air which prevents uniform heat distribution within the sphere or rather slow distribution occurs. As it has less matters, so less molecular bond energy need to break and so the expansion is rapid. Instead of expansion, you might see explosion upon strong heating.
If the radius of a circle is 10 cm then how many circles of radius 2 cm will be made from that circle?
Cookies!!!!I love cookies don’t you??Well, you must be thinking that I am insane. But trust me. This is the exact reason we learn maths at school.Let’s say we have a conversation between a mom and her son.Mom “I am making some cookies. Would you like some?”Son “Mom can I make them today?”“Sure son!”“Great! Where do I start?”They both make the dough, add chocolate chips (yummm!!!!) and flatten it out.“Get the stencil”“Ok mom. But how many will we make out of this?”“Great question!!! Now let’s do some magic…The diameter of this flat circular dough, is 20cm, so how much would be the radius?”“10cm”“Great!! Now what would be the area of this dough?”“Ummm…. That would be 100pi”“Exactly. Now what is the area of the stencil?”“The radius is 2cm, so area would be 4pi”“Excellent! Now if you cut this dough with this stencil, how many circles would you make to make perfect cookies?”“I guess 25?”“You would get 25 cookies after remoulding the leftover into another circles, and reshaping them until you get perfect 25”“So?”“How many would you get in the first dough circle?”“I can fit 5 circles from top to bottom, 3 beside them in each side, and yet another one beside the 3, so I get 13!”“Great!!! You learn fast!!”And that boy was an ideal kid for his mom.Note : I am not sure of the math…please suggest edits