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Curvilinear Motion [Kinetics]

December 8, 2016
Published By : Pratik Kataria
Categorised in:

Steps for application:
1. Draw F.B.D of particle
2. Apply D’Alembert’s force m x $a_N$ = ${m v^2 }/{ρ}$ in opposite direction of $a_N$ (i.e. away from centre of curvature)

3. Apply Σ$F_N$ = 0


Some important concepts:

(a) When particle is moving along a horizontal circle, mark y axis and normal axis in F.B.D.


(b) When particle is moving along a vertical circle, mark normal and tangential axis in F.B.D.

(c) When a particle attached by a string and whirled in verticle circle

$T_{top} = {mv^2}/{r} – mg$


$T_{bottom} = {mv^2}/{r} + mg$

(d) When an aeroplane flying along a vertical circle, Reaction exerted by seat on the pilot is,

$R_{top} = {mv^2}/{r} – mg$


$R_{bottom} = {mv^2}/{r} + mg$

(e) The normal reactions for a car in following three cases are
$R_1 = mg – ma_N$
$R_2 = mg$

$R_3 = mg + ma_N$

$R_3 > R_2 > R_1$


∙ At top of the path when car lost its contant, R = 0

$mg = ma_N$

$mg = {mv^2}/{r}$

$V_{max} = √{gr}$


∙ When a particle tied with a string and revolves in a vertical cricle

$v_{min} = √{gr}$ to remain in contact with circle
and $v_{bottom} = √{5gr}$

∙When a block is placed on a horizontal turn table at a distance r
The condition for the block not to slip.
$v_{max} = √{μ_s gr}$


∙ When a block is released from top of a cylinder, it will leave the cylinder

When $θ = cos^{-1} (2/3)$

∙ In above case, when it leaves the surface at B, Normal reaction is zero.


∙ When a pendulum is released from horizontal position

At lowest position
$v = √{2gL}$ and T = 3mg