help@askiitians.com

+91-87964 74404

Grade 12th passMechanics

Question is in the photo please help ??

Question image for Question is in the photo please help ??

Damini Parihar

11 Years agoGrade 12th pass

1 Answer

Sandeep Pathak

Approved Tutor Answer11 Years ago

There are three forces on the rod

Normal force, N between rod and surface – vertically upwards
Gravitational force, mg – vertically downwards
frictional force, f – horizontally towards right

Also, it is important to note that since there is no slip at the point of contact of rod with the surface, the rod is doing pure rotation about A which act as a hinge point. So direction of acceleration (Let’s call it a) is perpendicular to rod downwards.

Now it is straightforward to calculate a and limiting value of friction. Let’s apply equation of motion for translation in horizontal and vertical directions:
$f=ma\sin\theta\\ mg-N=ma\cos\theta$
Using $f=\mu N$ , we get
$a = \frac{\mu g}{\mu\cos\theta+\sin\theta}$

Now, considering moment of mg about A, we get
$mg\cos\theta\times \frac{L}{2}=I\alpha=\frac{mL^2}{3}\times\frac{a}{L/2}\Rightarrow a = \frac{3g}{4}\cos\theta$
Using two expressions for a, we get
$\mu = \frac{3\sin\theta\cos\theta}{4-3\cos^2\theta}$

Instantaneous acceleration of COM is a, while that of B is 2a using $a=r\alpha$ .

Three identical balls are placed on a frictionless horizontal surface touching each other. They stick to each other because of adhesive. Another ball of same radius and mass m is placed over the void created by the three balls. Find the forces applied by the balls kept on the floor to each other if the system remains in equilibrium.

mechanics

1 Answer Available

Last Activity: 10 Months ago

A car loaded with water having total mass 1000 kg moves on a straight horizontal Road starting from rest under the action of a force of 100 Newton. The water spills throw a small hole in the bottom at a rate of 0.1 KG per second the velocity of cart after 300 seconds is nearly.

11
21
31
41

mechanics

1 Answer Available

Last Activity: 10 Months ago

A metal strip clamped at one end vibrates with a frequency of 20 Hz and amplitude of 5 mm
at the free end, where a small mass of 2 g is positioned. determine
(i) The velocity of the end when passing through the zero position
(ii) The acceleration at maximum displacement
(iii) The maximum kinetic energy of the mass

mechanics

2 Answers Available

Last Activity: 3 Years ago

An object of mass m = 0.25 kg oscillates in a fluid at the end of a vertical spring of spring
constant kH = 85 N/m, see Fig.1. The effect of the fluid resistance is governed by the
damping constant b = 0.07kg/s.
(i) Find the period of the damped oscillation.
(ii) By what percentage does the amplitude of the oscillation decrease in each cycle?

mechanics

1 Answer Available

Last Activity: 3 Years ago

If a=x² find the displacement at t =3sec if body velocity at t= 0 sec is 0

mechanics

1 Answer Available

Last Activity: 3 Years ago

View all Questions