Answer:
Explanation:
Given

Motor reverse its direction when \omega =0



(b)





Red is refracted the least and violet is refracted the most
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

26.54 m/s is the magnitude of its velocity just before it strikes the ground
h=100m,v=20m/s,g=9.8m/s
time it takes to reach the ground,
![[t=\sqrt2h/g],[=\sqrt2*100/9.8=4.51s]](https://tex.z-dn.net/?f=%5Bt%3D%5Csqrt2h%2Fg%5D%2C%5B%3D%5Csqrt2%2A100%2F9.8%3D4.51s%5D)
x= 120m
t= 4.52
v= x/t
v= 120/4.52
v= 26.54 m/s
The "speed at which an object changes its location" can be expressed using a vector number called velocity. Consider a person who moves swiftly while taking two steps forward and two steps back while remaining in one location. Velocity is a vector quantity. Therefore, velocity is cognizant of direction. The direction must be taken into account when determining an object's velocity. A speed of 55 mph is not enough information. The direction must be used to appropriately depict the item's velocity. Simply said, the direction of the velocity vector indicates the direction of motion of an object.
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The horizontal force is m*v²/Lh, where m is the total mass. The vertical force is the total weight (233 + 840)N.
<span>Fx = [(233 + 840)/g]*v²/7.5 </span>
<span>v = 32.3*2*π*7.5/60 m/s = 25.37 m/s </span>
<span>The horizontal component of force from the cables is Th + Ti*sin40º and the vertical component of force from the cable is Ta*cos40º </span>
<span>Thh horizontal and vertical forces must balance each other. First the vertical components: </span>
<span>233 + 840 = Ti*cos40º </span>
<span>solve for Ti. (This is the answer to the part b) </span>
<span>Horizontally </span>
<span>[(233 + 840)/g]*v²/7.5 = Th + Ti*sin40º </span>
<span>Solve for Th </span>
<span>Th = [(233 + 840)/g]*v²/7.5 - Ti*sin40º </span>
<span>using v and Ti computed above.</span>