Why do we call Physics an exact Science?

Give two approaches to study Physics.

Which group of Physics has recently came into existence?

Name the scientific principle behind the technology, 'nuclear reactor'.

Give one major discovery resulted due to basic laws of electricity and magnetism.

Can gravitational force exist without any physical contact between acting bodies?

The mass of a body is measured by two persons is 0.2 kg and 10.23 kg.Which one is more accurate and why?

Which of the following length measurement is most accurate and way?
(i) 2.0 cm  
(ii) 2.00cm
(iii) 2.000cm

Round off to four significant figures
36.879

Round off to four significant figures
1.0084

A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance ?

A jeweller put a diamond weighing 5.42 g in a box weighing 1.2 Kg. Find the total weight of the box and the diamond to correct number of significant figures.

Express an acceleration of 10 m/s² in km/h².

A student measures the thickness of a human hair by looking at it through a microscope of magnification 100. He makes 20 observations and finds that the average width of the hair in the field of view of the microscope is 3.5 mm. What is the estimate on the thickness of hair ?

The photograph of a house occupies an area of 1.75 cm² on a 35 mm slide. The slide is projected on to a screen, and the area of the house on the screen is 1.55 m² . What is the linear magnification of the projector-screen arrangement.

The distance of venus from sun 1.082 x 10¹¹ is and its period of revolutions is 244.633 days. If the period of revolution of the earth around the sun is 365.247 days. Calculate the distance from the sun.

Why parallax method cannot be used for measuring distances of stars more than 100 light years away?

Explain this common observation clearly : If you look out of the window of a fast moving train, the nearby trees, houses etc. seem to move rapidly in a direction opposite to the train’s motion, but the distant objects (hill tops, the Moon, the stars etc.) seem to be stationary. (In fact, since you are aware that you are moving, these distant objects seem to move with you).

The angle subtended by the moon at a point on the earth is 0⁰31'. If the distance of the moon from the earthis 3.84 x 10⁸m. Find the diameter of the moon.

A LASER is a source of very intense, monochromatic and unidirectional beam of light.These properties of a LASER light can be exploited to measure long distances.The  distance of moon from the earth has been already determined very precisely using a LASER as a source of light. A LASER light beamed at the moon takes 2.56 s to return after reflection at the moon's surface.How much is the radius of lunar orbit around the earth?
This question is based on echo i.e., reception of reflected waves.Radius of the lunar orbit around the earth = Distance the moon and the earth.

Write in about 1000 words, a fiction piece based on your speculation on the science and technology of the twenty second century.

Attempt to formulate your moral views on the practice of Science. Imagine yourself stumbling upon a discovery, which has a great academic interest but is certain to have nothing but dangerous consequences for the human society. How, if at all, will you resolve your dilemma?

India has had a long and unbroken tradition of great scholarship in Mathematics, astronomy, linguistics, logic and ethics. Yet, in parallel with this, several superstitious and obscurantistic attitudes and practices flourished in our society and unfortunately continue even today among many educated people too. How will you use your knowledge of science to develop strategies to counter these attitudes?

Though the law gives women equal status in India, many people hold unscientific views on a woman's innate nature, capacity and intelligence and in practice give them a secondary status and role.
Demolish this view using scientific arguments and by quoting examples of great women in science and other spheres and persuade yourself and others that given equal opportunity, women are on par with men.

The shells of crabs found around a particular coastal location in Japan seem mostly to resemble the legendary face of a Samurai. Given below are two explanations of this observed fact. Which of these strikes you as a scientific explanation?
(a) A tragic sea accident several centuries ago drowned a young Samurai. As a tribute to his bravery, nature through its inscrutable ways immortalized his face by imprinting it on the crab shells in that area.
(b) After the sea tragedy, fishermen in that area, in a gesture of honour to their dead hero, let free any crab shell caught by them which accidentally had a shape resembling the face of a Samurai. Consequently, the particular shape of the crab shell survived longer and therefore in course of time the shape was genetically propagated. This is an example of evolution by artificial selection.
[Note: This interesting illustration taken from Carl Sagan's 'The Cosmos' highlights the fact that often strange and inexplicable facts which on the first sight appear 'supernatural' actually turn out to have simple scientific explanations. Try to think out other examples of this kind].