Question

Work done by the force of friction is what zero negative or positive

Answer 1

$\huge\mathfrak\red{Answer}$

WORK DONE

WORK DONE IS ACTUALLY THE PRODUCT OF FORCE ACTING ON THE BODY WITH DISPLACEMENTS OF THE BODY AND THE SIGN CONVENTION IN

THIS CASE IS VERY SIMPLE.

IN REALITY IF f FORCE IS APPLIED ON THE BODY A WHICH MAKES AN ANGLE $ WITH THE DISPLACEMENT THAN WORK DONE IS...

W=f.s Cos$

IF $ IS MORE THAN 90 THAN WORK DONE IS NEGATIVE

FIRSTLY I MAKE SURE THAT YOU KNOW THAT FRICTIONAL FORCE IS APPLIED AGAINST NET MOTION BETWEEN THE SURFACE IN CONTACT.

IN MANY CASE YOU SEE THAT THE FRICTIONAL FORCE IS RESPONSIBLE FOR STOPPING. THE MOTION OF THE BODY SO WORK DONE IN ALL THE CASES IS NEGATIVE BECAUSE ANGLE BETWEEN THE FRICTIONAL FORCE AND DISPLACEMENT IS MORE THAN 90°.

BUT IN HIGHER CLASSES YOU COME TO KNOW THAT FRICTIONAL FORCE NOT ALWAYS OPPOSE THE MOTION BUT IN SOME CASSES IT SUPPORT THE MOTION SO IN SUCH CASES THE WORK DONE IS POSITIVE BECAUSE THE ANGLE IS 0°.

AND WORK DONE BY FRICTIONAL FORCE IS ZERO WHEN THE BODY IS AT REST ON ROUGH SURFACE.

Answer 2

work done by friction is always either zero or negative this is dur to this fact

1. since friction always apposes the motion of an object frictional force direction will always be opposite to the direction of the motion of the object

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