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Answers
✌ANSWER ✌
Q.no.-- 6 -- answer
Dry Ice is a common name of solid carbon dioxide. its advantage include lower temperature then that of water ice and not leaving any residue.
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Q3 :- a train covers half of its journey with the speed of 30 metre per second and other half with the speed of 40 metre per second calculate the speed of the train during the whole journey ?
Ans :- Let the total distance it covers be 2x
Time taken to cover the first half of distance t1 = x/30
Time taken to cover the next half of distance t2 = x/40
Total time taken = t1 + t2
= x/30 + x/40
= 7x/120
Average speed = total distance/total time taken
= 2x/(7x/120)
= 240/7 ms^-1
= 34.3 m/s
Q4 :- state the types of motion shown by a freely falling stone?
Ans :- uniform motion as there is no force acting on ball except gravitational force.
Q5 :- derive the second equation of motion for a moving object ?
Ans :- First equation of motion,
v = u + at
=> v2 = u2 + 2uat + (at)2
=> v2 – u2 = 2uat + a2t2 …………..(1)
Third equation of motion,
v2 = u2 + 2as
(1) => 2uat + a2t2 = 2as
=> s = ut + ½ at2
This is the second equation of motion.
Q6 :- what is the common name of solid carbon dioxide give its one major use?
Ans :- The common name of solid CO2 is Dry Ice.
Q7 :- what is the effect on boiling point of pure water and highly explain with reason ?
Ans :- At the sea level boiling point of water is exactly 100 degree C. but pressure decreases with increasing elevation. Thus at higher altitudes, there is less pressure as compared to the ground level. Boiling point is the temperature when the pressure of the substance equals the atmospheric pressure. When there is less atmospheric pressure, obviously the boiling point will also be low.
Q8 :- Two ML dettol is poured in 500 ml of water measuring cylinder list the changes observed in a appearance smell change in volume n type of solution for metal suitable reasoning explanation ?
Ans :- the particles of true ml of medicine are evenly spread in 500 ml of water the process of diffusion the particles of dettol occupied the empty speed between the particles of water even if we take any of water we find the colour as same.
Q9 :- doctors advice to put a wet strip of cloth over forehead of a person having high fever give its scientific reason?
Ans :- When a person has fever, his body temperature becomes more than the normal body temperature. If we put the wet stripe of the cloth on his forehead, the water evaporates and absorbs the heat from his body that causes cooling and lowers his body temperature. That is why, Doctors advise us to put wet stripes on the forehead of a person having high fever.
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