define mechanical work write an expression for calculating - Physics - Energy and Power

Question

define mechanical work write an expression for calculating

Debalina Deb · Accepted Answer

Solution
The mechanical work = force*displacement
Work is said to be done when a force produces a displacement in
the body and acts in any direction except perpendicular to the
direction of displacement
Hence, the unit of work is Nm In the
honour of physicist James P Joule, the SI unit of work is written
as Joule (J)
Hence, 1 J = 1 Nm
1 Joule is defined as the amount of work
done by a unit force such that it displaces an object by a distance
of 1 m
Work is said to be done when a force is responsible for a
displacement Mathematically, work done is the scalar product of
force and displacement
W = F d (bold letters represent vector
quantities)
=> W = Fd (cos θ) (θ is the angle between force
and displacement)
<img alt="" height="138" src=
"https://s3mn%20mnimgs%20com/img/shared/discuss_editlive/2191102/2012_03_03_23_51_46/hckuhzfu5694784949235822004%20jpg"
width="408">
If the angle between force and displacement is an acute angle,
then θ is less than 900 and (cos θ) is
positive Hence work done is positive
Example: When you push a box and the box starts moving along the
direction of your force, the work done by you is positive Here, the
angle is 00
If the angle is obtuse, then it is greater than 900
and can be expressed as (θ + 900) Since, cos
(θ + 900) is negative The work done comes out to
be negative
Example: When you hit a coin and make it move in the table, the
coin move for a small distance and then stops The force of friction
between the surface of the coin and the table opposes the motion of
the coin The direction of friction and displacement of the coin are
opposite The work done by the friction is negative The angle here
is 1800