a block of mass 1 Kg is placed on the rough floor of a lift.The coefficient of friction between the block and the floor is 0.3.When the lift falls freely the block is pulled horizontally on the floor. what will be the force of friction?
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Given a block of mass 1 Kg is placed on the rough floor of a lift.The coefficient of friction between the block and the floor is 0.3.When the lift falls freely the block is pulled horizontally on the floor, the force of friction will be.......
here they have given that the lift falls freely, as the lift falls we can think that there is no gravity which means gravity is zero. When the gravity is zero, the weight is also zero. When weight is zero we can naturally think that force of friction is zero.
But we can calculate assuming the lift on the block.
We have coefficient of friction is 0.3, mass is 1 kg
Frictional force = μ x m x g
Force = 0.3 x 1 x 9.8
Force = 2.94 N
The force of friction experienced by the block will be zero.
when the lift falls freely then net acceleration due to gravity experienced by the block is zero.
acceleration due to gravity = g
acceleration due to free fall = -g
hence net acceleration experienced by the block = g + -g = 0
we know that frictional force,
f = μmg
= 0.3 x 1 x 0
= 0
Hence the force of friction will be zero.