Question

a wooden block having a mass of 1kg is placed on a table .the block just starts to move ,when a force of 10N is applied at 45°to the vertical to pull the block . the coefficient of friction between the table and the block​

Answer 1

Answer:

This is actually a tricky one since many people will end up getting

minimum force as f=μ.mgf=μ.mg

However Just read the question again , it says minimum force (There is no mention of minimum horizontal force)

Now as we know Friction force∼Normalforce∼Normal

i.e. : if we minimize the normal reaction we can minimize the friction at the same time we also need to provide enough Horizontal force to ensure block gets a horizontal velocity

Something like shown in figure !

Now the task is to find optimal angle “x” and Magnitude F

Applying simple physics : (Assuming Normal reaction from surface is N)

Balancing Vertical force

Fsinx+N=mgFsinx+N=mg —>(1)

N=mg−FsinxN=mg−Fsinx