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प्रश्न
Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):-
the wind speed during a storm
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उत्तर १
Wind speed during a storm can be measured by an anemometer. As wind blows, it rotates. The rotation made by the anemometer in one second gives the value of wind speed.
उत्तर २
Wind speed can be estimated by floating a gas-filled balloon in air at a known height h. When there is no wind, the balloon is at A. Suppose the wind starts blowing to the right such that the balloon drifts to position B in 1 second.
Now, AB = d = hθ.
The value of d directly gives the wind speed.
संबंधित प्रश्न
What do you mean by significant figures?
How many significant figures are present in the 0.0025?
How many significant figures are present in the 208?
Round up the following upto three significant figures:
0.04597
How many significant figures should be present in the answer of the following calculation?
0.0125 + 0.7864 + 0.0215
The relative density of lead is 11.3. Its density is ______ g cm–3or ______ kg m–3.
You are given a thread and a metre scale. How will you estimate the diameter of the thread?
The mass of a box measured by a grocer’s balance is 2.300 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to the box. What is
- What is the total mass of the box?
- What is the difference in the masses of the pieces to correct significant figures?
Precise measurements of physical quantities are a need of science. For example, to ascertain the speed of an aircraft, one must have an accurate method to find its positions at closely separated instants of time. This was the actual motivation behind the discovery of radar in World War II. Think of different examples in modern science where precise measurements of length, time, mass etc. are needed. Also, wherever you can, give a quantitative idea of the precision needed.
State the number of significant figures in the following:
6.320 J
State the number of significant figures in the following:
0.0006032 m2
A large ball 2 m in radius is made up of a rope of square cross-section with edge length 4 mm. Neglecting the air gaps in the ball, what is the total length of the rope to the nearest order of magnitude?
Solve the numerical example.
Write down the number of significant figures in the following: 0.003 m2, 0.1250 gm cm-2, 6.4 x 106 m, 1.6 x 10-19 C, 9.1 x 10-31 kg.
Which of the following has the highest number of significant figures?
Write the rules for determining significant figures.
Calculate the length of the arc of a circle of radius 31.0 cm which subtends an angle of `pi/6` at the centre.
What is the least count of a measuring instrument?
How many significant figures are there in the number 0.001405?
