A metal of block of mass 10kg lies on a rough plane, horizontal force of 8n applied to the block through it's centre of mass just slides the block on the plat form. What is the coefficient of limiting friction between the block and the plat form.

Wb = M*g = 10 * 9.8 = 98 N. = Normal force, Fn.

Fs = Force of static friction.

Fap-Fs = M*a.
8 - Fs = M*a = M*0 = 0.
Fs = 8 N.

Fs = u*Fn = 8 N.
u = 8/Fn = 8/98 = 0.082.

To find the coefficient of limiting friction between the block and the platform, we need to use the concept of friction and the given information.

Friction is the force that opposes the relative motion or tendency of motion between two surfaces in contact. The maximum value of friction that can occur between two surfaces is known as the limiting friction. It is given by the equation:

Limiting Friction (F) = coefficient of limiting friction (μ) × Normal force (N)

In this case, the frictional force is what prevents the block from sliding on the platform until the applied force is 8 N.

The normal force (N) acting on the block is equal to its weight. Since the block is on a horizontal plane, the weight is equal to the mass of the block (m) multiplied by the acceleration due to gravity (g):

Weight (N) = mass (m) × acceleration due to gravity (g)
Weight (N) = 10 kg × 9.8 m/s^2
Weight (N) = 98 N

Now, we can use this information to find the coefficient of limiting friction:

Limiting Friction (F) = coefficient of limiting friction (μ) × Normal force (N)
8 N = μ × 98 N

Solving for the coefficient of limiting friction:

μ = 8 N / 98 N
μ = 0.0816

Therefore, the coefficient of limiting friction between the block and the platform is approximately 0.0816.