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Showing posts with the label Physics

### What is big bang?

Big bang is the phenomena where the galaxies goes further from one another. In 1924, scientist Hubble Showed that the universe is gradually expanding. Meaning, once in the past the whole universe was in one single point. After the massive explosion, that is big bang, the whole universe began expanding. This expansion will never stop and everything will go apart from others.

### Technology may be advantageous harmful but knowledge can never be harmful- discuss this thought based on physics.

From hundred years scientist have researched and gathered knowledge from their surroundings. Technology is the outcome of this knowledge. This technology can be both advantageous and harmful depending on its use. Any knowledge can be utilized in both ways. It depends on the invented technology from the knowledge. Example: Radioactive objects can be used in medical science as well as in destruction. So, knowledge can't be harmful. It is the technology invented from knowledge which can be harmful.

### Why mass and weight are not the same type of quantity?

Mass is unique property of an object. Mass is measure of how much matter an object has. It is independent of place, time and person. Weight as the force exerted on a body by gravity. It is a measure of how strongly gravity pulls on that matter. If mass on of a body is m and gravitational acceleration is g in a place, then weight of that body in that place is w=mg. For a specific / certain object, mass of that object is specific. As gravitational acceleration g varies with places, so, weight will not be same in different places.

### How can you understand that a slide callipers has an instrumental error?

The main scale of the slide callipers is made of a graduated rectangular still plate. A metal jaw is fixed at the starting end of the scale, that is, at the end marked '0' of the main scale. When the jaw of the vernier scale touches the jaw of the main scale then the zero of the main scale should coincide with the zero of the vernier scale. If two zeros are not marched, then we can understand that the slide callipers has an instrumental error.

### What do mean by 50J work?

50J work means, if a force of 1N is applied on a body, the body will get a displacement of 50m. Again, it can also be said that, if a force of 50N is applied on a body and the body gets a displacement of 1m, the amount of work done is 50J.

### Why a heavy weight is easy to lift in water?

In water, an upward force or buoyancy acts on any heavy object. For this reason a heavy object appears lighter when immersed in water and it becomes easy to lift it.

### Why the atmospheric pressure changes with the changes of altitude?

Atmospheric pressure depends on the altitude and density of air. With increasing height from sea level, gravitational acceleration and density of air decrease. For this reason, with increasing of height, the atmospheric pressure decreases. That is as we go upward from sea level atmospheric pressure decreases.

### Why we do not feel the atmospheric pressure?

The blood pressure inside our body is slightly larger than atmospheric pressure and the pressure acts along every direction equally. That's why we don't feel any pressure.

### What is apparent expansion of liquid?

The expansion of the liquid without considering the expansion of the container is called apparent expansion.

### What is Torricelli's vacuum?

If a one meter long glass tube opened at one end filled with mercury is put into a mercury filled container invertedly and perpendicularly due to air pressure the mercury level comes down. At a certain level it becomes steady which means a portion of tube's upper area becomes vaccum. This vaccum is known as Torricelli's vaccum.

### The cause of flotting and sinking of a body.

If an object is put into still water and the amount of replaced water by the object is less than objects mass it will down, if the replaced water has same mass as the object it will float while its body will be fully drowned. Again, if the amount of replaced water is more than the objects mass it will float while a part of its body is drowned.

### The condition of the floating or immersion of a body.

The conditions of the floating or sinking of an object are-If W1>W2, or if the weight of the object is more than liquid abstracted by the object than the object will sink in the liquid.If W1=W2, or if the weight of the object is equal to the liquid abstracted by the object will float in a completely submerged state.If W1<W2, or if the weight of the object is less than the liquid abstracted by the object will float in a partially submerged state.

### Plasma state of substance

The forth state of substance is plasma. This plasma is the ionized gas in very high temperature. A massive source of plasma is sun. Also other states are sources of plasma. Plasma state is generated in a state of few thousand degree Celsius temperature.

### Law of increasing force

If at the smallest portion of a liquid some force is applied with a piston, than the bigger pistons will feel a much greater force than the applied force.

### How stress leads to strain?

The change per unit length or per unit volume of an object is called stain. Again internal restoring force acting perpendicularly per unit area of the body is called stress. Whenever an external force deforms a body, strain develops. Again, applied external force for developing certain amount of stain is equal to the internal restoring force generated on the body. Manly, this force acts against the intermolecular force of molecules of that object and causes strain.

### Types of motion

Linear motion : If a body is in motion along a straight line, that is, if the motion of a body is restricted on a straight line its motion is called linear motion. The motion of a car in a straight street is linear motion.
Rotational motion : When a body rotates around a particular point or an axis keeping the distance of the particles of the body unchanged is called rotational motion. For example, the motion of an electric fan, the motion of the heads of a clock.
Rectilinear motion : When a body moves along a straight line in such a way that each particle of the body travels the same distance at the same time in the same direction. If a book is pushed to shift from one end to the other of a table without rotation, the motion will be rectilinear because all the particles of the book travel the equal distance, at an equal time in the same direction.
Periodic motion : If the motion of a moving particle is such that it passes through a definite point along the path of its motion in the same…

### Error and accuracy in measurement

All measurements have some limitations of accuracy. The accuracy of the measurement depends on the skill of the observer and the instruments used. Suppose a meter scale is graduated in centimeter and millimeter. If we want to measure the length of this book we will get the result probably up to 0.1cm accurately. Accuracy may be reduced in case of measuring the length of a house because the scale is to be used several times for measuring the full length. Every time the position of the front edge of the scale has to be a marker on the floor. This increases the source of error thus increasing the probability of errors.
The accuracy of measurement is as important as the measurement itself. So, the observer should mention the degree of accuracy of the result with the result of the experiment. Let the length of this book be 26.0cm ± 0.1cm. Here the symbol ± means that the real length of the book is between 25.9cm and 26.1cm. Here 0.1cm is the uncertainty or error of measurement. Generally, th…

### What is CT scan? CT scan is the abbreviation of the word Computed Tomography Scan. Tomography means to create an image of the slice (or two-dimensional part) of a three-dimensional object. 