3. 10,000 screws

3.In a production line, 10,000 small screws are to be sorted into packs of 50 each. Manual counting would be too tedious. suggest ways to solve this.

Either a weighing scale or an electromagnet can be used to solve this problem.

First method useing the electromagnet:

Firstly, we must adjust the voltage (resistance) of the electromagnet such that the electromagnet would attract the 'right' amount of screws.

Although this is one method, there is still one disadvantage of using it.

It was stated that adjust the voltage until it is able to attract only 50 screws, but how is that possible?
(It should not be possible as it would either attract all the screws or none.)

It is true that using a magnet is an easier way, but the electromagnet would attract indefinate amount of screws, in the end, we still have to count it again.



The other method is using the weighing scale which I personally think is a better way.

Firstly, we would have to count 50 screws and weigh them. Record the it down. Estimate the number of screws or take a handful of it and place it on the weighing scale. Either take away screws or add screws until you get the previous weight of 50 screws.Continue doing so until all screws are used up.

2. submarines

2.How do submarines float and sink at will?

Each submarines have ballasts tank in them. As you may ask what is a ballast tank,a ballast tank is a tank that allows the submarine to float or sink. Each ballast tank contains both air and water.

To sink, air is let out of the tank and water is let in.

To float back up, more air is pumped into the tank,causing it to be lighter,less dense.

As water is let in, it becomes heavier and thus, it becomes denser and would sink.This is a picture of a ballast tank used in a submarine.

In order for the submarine to maintain constant depth throughtout the whole journey, the ballast tank must have the same certain amount of water and air. This is called NEUTRAL BUOYANCY.

This is a whole diagram of a submarine. There are two ballast tanks. One of it is the main ballast tank while the other is the aft ballast.

AN ACCIDENT THAT RESULTED DEATH:

--An accident occured 9 years ago (2000). A Russian submarine K-141 had sunk while preparindg to fire dummy torpedoes.

It is believed that a chemical ,used as a propellant for the torpedo, seeped through rust in the torpedo casing.

Another belief is that a chemical cartridge came in contact with water that had cause chemical reaction and flash fire.

Fortunately, 23 out of 118 sailors had survived the attack and even stayed at compartment 9 at the aft of the boat for a few hours after the blast.

There were arguments about survivers still living after the blast but was later confirmed with evidence from Captain Lieutenant Dmitry Kolesnikov, one of the remaining survivers. He had written notes about his stay. The unfortunate event was that they had died hours later.

Tragedy broke out on the Summer of August 12, 2000. The ship could resist no more and SUNK! The news had spread throughout the world and it has devastated everyone-nobody expected it to happen. Shortly after two years later (2002), it was confirmed that a faulty torpedo had sunk KURSK.

1. MacRitchie Reservoir

As you can see, the shape of the reservoir is disproportioned and cannot be calculated using normal methods.
1.Estimate the amount of water in the MacRitchie Reservoir during the dry season if the depth is 2.5m.

There are two solutions to this question but the first method would be the most appropriate solution of the two.

Method 1: By using method 1, we would get a more accurate solution. For this question,a cuboid is used.

Given the dimension of Macritchie Reservoir, all we have to do is multiple the length, breadth and height/width/diameter.

In this case, the approximate length,breadth and diameter is :

Length ____(2cm) 120000cm,

Breadth____(1.4cm) 84000cm

Diameter____250cm

(Measurements are according to measurements on map)

(1 cm is approximately 60,000 cm)

As the shape of the reservoir is taken after the shape of a rectangle while the area of the cuboid is taken after a square, some parts of the rectangle should fit into the square, making it an approximate area. Thus, if you find the product of the length, breadth and width,you would be able to get an approximate amount of water during a dry season.

(The 'cut and paste' method)

Method 2: Method 2 is the use of a cylinder.The solution to finding the volume of Macritchie Reservoir is TT x R x R x H . In this case, the radius is 125 cm , the height is 75,0000cm, and TT is 3.14cm.

Although it is one of the method, the answers of both methods are totally different. If you use a cylinder to calculate the volume of the water, the circular portion of the cylinder would be on the water and instead of a flat surface of water, there would be a semi-circle floating on the water.

If you were to use this method, the solution would be

(TT) 3.14cm x (R) 125cm x (R)125cm x (H) 750000cm = 7359375 thousand ml. (estimated value is 7.4 million)

If both of them were to be compared, method one would be a more understandable solution to solve this type of questions.

Readable stuffss 0.0

Finally,it is created. I had a hard time finding a good place to do this physics blog.Now after creating this blog, i hope that those who read this blog will learn something new. Looks like I would need to go onto this blog almost everyday. I hope that those who read this blog will give positive comments about it !! Correct me if possible. Have a nice time reading this blog that would last me through many years. Have a good time !:@)