Answer:
11760J
Explanation:
Given parameters:
Height of hill = 30m
Weight = 40kg
Unknown:
Gravitational potential energy = ?
Solution:
To find the gravitational potential energy, it is the energy due to the position of a body;
G.PE = mgh
m is the mass
g is the acceleration due to gravity
h is the height
Now insert the parameters and solve;
G.PE = 40 x 9.8 x 30 = 11760J
Open circuit ......fiend do
The general formula to calculate the work is:

where F is the force, d is the displacement of the couch, and
is the angle between the direction of the force and the displacement. Let's apply this formula to the different parts of the problem.
(a) Work done by you: in this case, the force applied is parallel to the displacement of the couch, so
and
, therefore the work is just equal to the product between the horizontal force you apply to push the couch and the distance the couch has been moved:

(b) work done by the frictional force: the frictional force has opposite direction to the displacement, therefore
and
. Therefore, we must include a negative sign when we calculate the work done by the frictional force:

(c) The work done by gravity is zero. In fact, gravity (which points downwards) is perpendicular to the displacement of the couch (which is horizontal), therefore
and
: this means
.
(d) Work done by the net force:
The net force is the difference between the horizontal force applied by you and the frictional force:

And the net force is in the same direction of the displacement, so
and
and the work done is

Answer:
Torque, 
Explanation:
It is given that,
Length of the wrench, l = 0.6 m
Mass of the wrench, m = 100 kg
We know that the torque applied by mechanic is given by :




So, the torque applied by the mechanic is 588 N-m. Hence, this is the required solution.