A body of mass m and negligible size starts from rest and slides down the surface of a frictionless solid sphere of radius R. Prove that the body leaves the sphere when 0 = cos(2/3).

Respuesta :

Answer:

[tex]\theta=\cos^{-1}\dfrac{2}{3}[/tex]

Explanation:

Given that,

Mass = m

Radius = r

Angle [tex]\theta=\cos\dfrac{2}{3}[/tex]

Prove that,

The body leaves the sphere when [tex]\theta=\cos^{-1}\dfrac{2}{3}[/tex]

When the particle was contact

[tex]mg\cos\theta=\dfrac{mv^2}{R}[/tex]

[tex]Rg\cos\theta=v^2[/tex].....(I)

Using conservation of energy

[tex]mg(R-R\cos\theta)=\dfrac{1}{2}mv^2[/tex]

[tex]v^2=2gR(1-\cos\theta)[/tex]....(II)

From equation (I) and (II)

[tex]Rg\cos\theta=2gR(1-\cos\theta)[/tex]

[tex]\cos\theta=2-2\cos\theta[/tex]

[tex]\theta=\cos^{-1}\dfrac{2}{3}[/tex]

The body leaves the sphere when [tex]\theta=\cos^{-1}\dfrac{2}{3}[/tex]

Hence proved.

The angle when the body leaves the sphere is [tex]\theta = cos^{-1} (\frac{2}{3} )[/tex], proved.

Force on the particle when it is stationary

The force on the particle when it is stationary is calculated as follows;

mgcosθ = mv²/R

v² = Rgcosθ  ---(1)

Conservation of energy

The final speed of the object when it starts to slide can be determimed using conservation of energy.

mg(R - Rcosθ) = ¹/₂mv²

v² = 2gR(1 - cosθ) ---(2)

solve (1) and (2) together

Rgcosθ = 2gR(1 - cosθ)

cosθ = 2 - 2cosθ

3cosθ = 2

cosθ = 2/3

[tex]\theta = cos^{-1} (\frac{2}{3} )[/tex]

Thus, the angle when the body leaves the sphere is [tex]\theta = cos^{-1} (\frac{2}{3} )[/tex], proved.

Learn more about conservation of energy here: https://brainly.com/question/166559

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