Chapter 16 Curvature-I

16.1 Exercise 9

16.1.1 Question 1

Find the radius of curvature at any point \((x,y)\) for the curve

  1. \(y^2 = 4ax\) (TU 2057)

  2. \(x^{2/3} + y^{2/3} = a^{2/3}\)

  3. \(y=c \cos \text{h} \left(\frac{x}{c}\right)\)

  4. \(xy=c^2\)

  5. \(x=a \cos \theta, y = a \sin \theta\)

  6. \(x = a \cos \phi, y = b \sin \phi\)

16.1.2 Question 2

In the cycloid \(x=a(\theta + \sin \theta), y = a(1-\cos \theta)\) at \(\theta =0\), prove that \(\rho = 4a\).

16.1.3 Question 3

Show that the radius of curvature at a point \((r, \theta)\) for the curve \(r=ae^{\theta \cot \alpha}\) is \(\rho = r \csc \alpha\).

16.1.4 Question 4

Find the radius of curvature of the curve \(r=a(1-\cos \theta)\).

16.1.5 Question 5

Show that the radius of curvature for the curve \(r^m = a^m \cos m \theta\) is \(\frac{a^m}{(m+1)r^{m-1}}\).

16.1.6 Question 6

Find the radius of curvature at the point \((p,r)\) of the curve \(r^{m+1} = a^m p\).

16.1.7 Question 7

Find the radius of curvature of the curve

  1. \(y^2 = 4x\) at the vertex \((0,0)\) (TU 2054)

  2. \(y^2 = \frac{a+x}{a-x}.x^2\) at the origin

16.1.8 Question 8

Show that for the ellipse \(\frac{x^2}{a^2} + \frac{y^2}{b^2}=1\), the radius of curvature at the extremity of the major axis is equal to half the latus rectum. (TU 2055)