find the value of the following
(g) (5 - 2)3 × 2 + [-4 + (-7)] ÷ (-2 + 4)
Answers
Answer:
Page No: 13
Exercises
1.1. Some of the most profound statements on the nature of science have come
from Albert Einstein, one of the greatest scientists of all time. What do you think
did Einstein mean when he said : “The most incomprehensible thing about the
world is that it is comprehensible”?
Answer
The Physical world around us is full of different complex natural phenomena so the
world is in-comprehensible. But with the help of study and observations it has
been found that all these phenomena are based on some basic physical laws and
so it is comprehensible.
1.2. "“Every great physical theory starts as a heresy and ends as a dogma"”. Give
some examples from the history of science of the validity of this incisive remark.
Answer
The statement above is true. Validity of this incisive remark can be validated from
the example of moment of inertia. It states that the moment of inertia of a body
depends on its energy. But according to Einstein's mass-energy relation (E = mc2),
energy depends on the speed of the body.3. "“Politics is the art of the possible"”. Similarly, “"Science is the art of the
soluble"”. Explain this beautiful aphorism on the nature and practice of science.
Answer
It is well known that to win over votes, politicians would make anything and
everything possible even when they are least sure of the same. and in Science the
various natural phenomena can be explained in terms of some basic laws. So as
'Politics is the art of possible' similarly 'Science is the art of the soluble'.
1.4. Though India now has a large base in science and technology, which is fast
expanding, it is still a long way from realizing its potential of becoming a world
leader in science. Name some important factors, which in your view have hindered
the advancement of science in India.
Answer
Some important factors in our view which have hindered the advancement of
science in India are:
→ Proper funds are not arranged for the development of research work and
laboratories. The labs and scientific instruments are very old and outdated.
→ Most of the people in India are uneducated and highly traditional. They don't
understand the importance of Science.
→ There is no proper employment opportunity for the science educated person in
India.
→ There are no proper facilities for science education in schools and colleges in
India.
1.5. No physicist has ever "“seen"” an electron. Yet, all physicists believe in the
existence of electrons. An intelligent but superstitious man advances this analogy to argue that ‘ghosts’ exist even though no one has '‘seen'’ one. How will you
refute his argument?
Answer
No physicist has ever seen an atom but there are practical evidences which prove
the presence of electron. Their size is so small, even powerful microscopes find it
difficult to measure their sizes. But still its effects could be tested
On the other end there is no phenomena which can be explained on the basis of
existence of ghosts.
Our senses of sight and hearing are very limited to observe the existence of both.
So there is no comparison between the two given cases.
1.6. 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 honor 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].
Answer
Answer:
10.5
Step-by-step explanation:
(5-2)3×2+[-4+(-7)]÷(-2+4)
3×3×2+[-4-7]÷2
3×3×2-4-7÷2
3×3×2-4-3.5
18-4-3.5
10.5