Question

A disc of mass m is rolling without slipping on a rough surface. The velocity of
centre of mass of disc is 10 m/s. Find the velocity of point A which makes an
angle 30º from horizontal as shown in figure
(A) V = 15i-3✓5j
(B) V = 15i +5✓3j
(C) V = 15i-5✓3j
(D) V = -15i-5✓3j
​

Answer 1

Answer:

v =15i-5√3j is the answer

Answer 2

Given:

Mass of disc = m

Vcom = 10m/s

To find:

The velocity of point A that makes an  angle 30º from horizontal

Solution:

Since the body is rolling without slipping

⇒Vcom  = Rω

where ω is the angular velocity and R is the radius

(Velocity of point A) Î = V + V sin 30°

= 10 + 10 sin 30°

= 15m/s Î

(Velocity of point A) j = - V cos 30°

= - 10 X √3/2

= - 5√3

Hence, the velocity of point A = (C) V = 15i-5✓3j