Answer:
Explanation:
The direction of force will be in upward direction making an angle of θ with the vertical .
Reaction force R = mg - F cosθ
Friction force = μR
= .36 (mg - F cosθ )
Horizontal component of applied force
= F sinθ
For equilibrium
F sinθ = .36 (mg - F cosθ)
F sinθ + .36 F cosθ =.36 mg
F (sinθ + .36 cosθ) = .36 mg
F R( cosδsinθ +sinδ cosθ) = .36 mg ( Rcosδ = 1 . Rsinδ= .36 )
F R sin( θ+δ ) = . 36 mg
F = .36 mg / Rsin( θ+δ )
For minimum F , sin( θ+δ ) should be maximum
sin( θ+ δ ) = sin 90
θ+ δ = 90
Rsinδ / Rcosδ = .36
δ = 20⁰
θ = 70⁰ Ans
Answer: choices a and b
Explanation:
Telescope can be defined as am optical instrument which is designed to observe the distant objects clear and nearer. It comprises of arrangement of lenses which allow the rays of light to be collected. The collected light is focused and the image so produced is magnified in the form of an image. The telescopes are prepared and manufactured on mountains top as this will help in preventing the distortion of light obtain from the star due to the fluctuation of air mass in the atmosphere. The atmospheric distortion affects the resolution, and affects the vision. The atmospheric pressure is low at the mountain tops so it will help in better observation of the sky.
The angle of the ladder inclined with respect to the horizontal after being moved a distance of 0.82 m closer to the building is 53.84°
cos θ = Adjacent side / Hypotenuse
θ
= 47°
Hypotenuse = Length of ladder = 8.5 m
cos 47° = Adjacent side / 8.5
Adjacent side = Initial distance of base of ladder from the building = 5.8 m
Adjacent side 2 = Final distance of base of ladder from the building
Adjacent side 2 = 5.8 - 0.82 = 4.98 m
cos θ
= Adjacent side 2 / Hypotenuse
cos θ = 4.98 / 8.5 = 0.59
θ = 
( 0.59 )
θ = 53.84°
The formula used above is one of trigonometric ratios. Trigonometric ratios can used only in a right angled triangle where one of the angles in at 90 degrees and the other two angles are less than 90 degrees.
Therefore, the angle of the ladder inclined with respect to the horizontal after being moved is 53.84°
To know more about trigonometric ratios
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<span>The true brightness of an object
is called its luminosity. It is the total amount of energy emitted by bright or
meteorological objects over a period of time. It has the SI unit of joules per
second or watts. So the answer is letter A. Intensity is the measure of how
strong the substance or object is when it projects something. Magnitude is a
measure of how great is the size the object produces. Viscosity is the measure
of flow of a substance.</span>
