# WHY DID BLOCK MOVED ?

TWO EQUALS...YET NOT!! I want to discuss why a tensional force on a block equal to the weight of block makes it move..though UNIFORMLY.

Suppose the block moves height h,by pulling the string in the upward direction, it gains a potential energy,thus we need to increase the force to move it in uniformly, thus, every fraction of second we need to increase the force applied.Now we cannot say that inertia keeps it moving in the required direction.So a force,GREATER THAN the weight force must be applied to keep it moving in upward direction. As my question was, why do we equate the force T to m*g although the block moved uniformly.

Note by Aman Kumar
6 years, 9 months ago

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We equal the force when there is no acceleration or block moving with constant velocity or at rest.

- 6 years, 9 months ago

when the block starts moving upward,it gains up a velocity from 0 to something, thus, it accelerates.

- 6 years, 9 months ago

Hope you understand.

- 6 years, 8 months ago

Initially it do accelerates

- 6 years, 8 months ago

Equal force on a block when it is in rest is simply its mass into acceleration due to gravity( If it is affected by any gravitation). Equal to the force when it is in motion means different. To move the block the force will not be equal but greater than the force exerted on the string by the block or whatever although it will be equal to the force exerted by the moving block if it moves at a constant speed.

- 6 years, 8 months ago

if tension equals the weight.Then net force on block is zero.If initially it is moving then it remain in motion without change in velocity.

- 6 years, 8 months ago

I AM EDITING THE QUESTION

- 6 years, 8 months ago

the ans is my friend.............. ma=T-mg but as it moves uniformly acceleration is ZERO. thus 0=T-mg T=Mg your concepts r not clear my friend pls read from a better source such as H C Verma

- 6 years, 8 months ago