Question

एक त्रिभुज की तीन भुजाएं क्रमश 6 सेंटीमीटर कोमा 11 सेंटीमीटर एवं 15 सेंटीमीटर हो तो उसका क्षेत्रफल ज्ञात कीजिए​

Answer 1

Answer:

Answer:

Angular retardation of flywheel = π/10  rad/s²

Explanation:

Given:-

Initial angular velocity of flywheel = 360 rpm

Final angular velocity of flywheel = 180 rpm

Time taken for change in angular velocity = 1 min = 60 sec

To find:-

Angular acceleration (retardation) of the flywheel, a =?

Formula required:-

Formula for angular acceleration

        a = Δω / Δt

[ where a is angular acceleration, Δω is change in angular velocity, Δt is change in time ]

Solution:-

Converting the angular velocities given in rpm into rad/sec

→ ω₁ = 360 rpm = 360 × 2π/60  rad/sec = 12π rad/sec

→ ω₂ = 180 rpm = 180 × 2π/60  rad/sec = 6π rad/sec

Calculating the angular acceleration

→ a = Δω / Δt

→ a = (12π - 6π) / (60)

→ a = -6π / 60

→ a = -π/10  rad/s²

Therefore,

Angular retardation of the flywheel is π/10  rad/s².Answer:

The work done by the moon when it revolves around the earth is zero because here displacement of moon and gravitational force of earth are perpendicular to each other.

i.e., Work done (W) =F×d×cosθ

where F = applied force

d = displacement of the body

θ = angle between the applied force and the displacement of the body

In the case of revolution of moon around the earth, θ is 90°. Thus, W=F×d×cos90°

 = F×d×0=0

So, the work done by the moon when it revolves around the earth is zero.

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