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The average velocity of a body can be zero, but average speed of a body cannot be zero.

 Speed indicates only the rate of change of position with time, it does not indicate the direction of change of position. The velocity states the rate of change of position along with its direction that is, velocity means the rate of change of position in a definite direction or in other words the rate of change of displacement. The average velocity depends on the net displacement of a body so if a body starts from a position and comes back to the same position after some time, the net displacement is zero. Consequently, the average velocity is zero. While the speed depends on the actual path length covered. It can't be zero if a body has displaced from its position. 

Explain if the falling mango supports third law

 Third law of falling bodies- The distance traversed by a freely falling body from rest in a given time is directly proportional to the square of the time.

Why the value of g is maximum at polar region?

The poles are closer to the center of the Earth due to the equatorial bulge, which strengthens gravitation at the poles and weakens it at the equator. The equatorial bulge modifies how the Earth gravitates. This is why the value of g is maximum in the polar regions.

The acceleration of falling body is uniform - explain.

If the rate of increase of velocity of a moving body in a particular direction constant all the time, then the acceleration is said to be uniform. Due to gravity, the acceleration of a freely falling body is 9.8 ms -2 , that is, its velocity increases by 9.8 ms -2  for each successive second. So, the acceleration of a falling body is uniform.

When does non-uniform acceleration take place?

Non-uniform acceleration takes place when the rate of increase of velocity changes with time.

Explain average speed.

If the magnitude of speed does not change during the motion of the body, the speed of the body is called uniform speed. If a body doesn't travel an equal distance in equal interval of time, the speed is called non-uniform speed. If the body doesn't move with uniform speed, the speed obtained by dividing the total distance traveled by time called average speed. So, Average speed = total distance / time.

Differences between velocity and speed

Differences between velocity and speed. No. Velocity Speed 1 Rate of change of position of an object in a definite direction is called velocity. Rate of change of position of an object in any direction is called speed.  2 Velocity is a vector quantity. Speed is a scalar quantity.

Why trees from outside of a moving bus seem moving.

From a moving bus, trees seem moving because of relative velocity. Every observer sees his own structure as non-moving. Passengers of a moving bus will see the bus as a non-moving object but he will think that the trees outside are moving.

What is the motion of simple pendulum oscillatory?

If an object in periodic motion moves in such a way that in half of its time period its motion is in a definite direction and in another half of the time period its direction of motion is opposite but the path is the same then its motion is called oscillatory. A simple pendulum moves in one direction in half of its time period and moves in the same path but in the opposite direction in the second half of the time period. For this reason motion of the simple pendulum is oscillatory. 

Why acceleration due to gravity is the example of uniform acceleration?

If the rate of increase of velocity of a moving body in a particular direction is maintained constant all the time, then the acceleration is said to be uniform. An example of uniform acceleration is the gravitational acceleration. Due to gravity, the acceleration of a freely falling body is 9.8 m/s2, that is, its velocity increases by 9.8 m/s for each successive seconds. So, gravitational acceleration is an example of uniform acceleration.  

What is random error?

The error for which an irrelevant measurement occurs in a measured result due to the precision limitations of the measuring device is known as a random error. In order to minimize the random error, the average value of frequent measurements has to be taken.

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. 

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