the terminal velocity of a falling body occurs during free fall when a falling body experiences zero...
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The terminal velocity of a falling body occurs during free fall when a falling body experiences zero
acceleration. This is because of the retarding force known as air resistance. Air resistance exists
because air molecules collide into a falling body creating an upward force opposite gravity. This upward
force will eventually balance the falling body's weight. It will continue to fall at constant velocity known as
the terminal velocity.
Terminal Velocity
After jumping from the aircraft the skydiver increasesspeed up to a steady maximum called terminal velocity.
The downward force of gravity (the Weight) is balanced by the upwardforce of air resistance (the Drag)
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A Hooke's Law Spring
Determine the Spring Constant
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Hooke's Law states that the restoring force of aspring is directly proportional to a smalldisplacement. In equation form, we write
F = -kx
where x is the size of the displacement. Theproportionality constant k is specific for eachspring.
The object of this virtual lab is to determine thespring constant k.
Displacement is measured in centimeters. Each ofthe blue weights has a mass of 50 grams. Thegray virtual weight hanger has no mass.
Snapshots of the lab are found in the four figuresthat follow.
50 grams mass is 2 cm displacement. 100 grams mass is 4 cm displacement.
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150 grams mass is 6 cm displacement. 200 grams mass is 8 cm displacement.
Mass(grams)
Displacement(cm)
50 2
100 4
150 6
200 8
These data have been entered into thetable to the left.
For each snapshot above the downwardpull of gravity is balanced by the upwardpull of the spring. A force or free-bodydiagram of this is shown on the right-hand side.
Note that the restoring spring force isgiven by Hooke's Law as kx.
Conservation of Energy with Examples
CONSERVATION OF ENERGY THEOREM
Nothing can be destroyed or created in the universe
like energy. Suppose that a ball falls from height of
2m, it has only potential energy at the beginning,
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however, as it falls it gains kinetic energy and its velocity increases. When it hits the
ground it has only kinetic energy. Well, where is the potential energy that it has at the
beginning? It is totally converted to the kinetic energy, as said in the first sentence
nothing can be destroyed or created they just change form. Thus, our potential energy
also changes its forms from potential to the kinetic energy. In summary, energy of the
system is always constant, they can change their forms but amount of total energy
does not change.
CONSERVATION
OF ENERGY
THEOREM
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Nothing can be destroyed or created in the universe
like energy. Suppose that a ball falls from height of
2m, it has only potential energy at the beginning,
however, as it falls it gains kinetic energy and its
velocity increases. When it hits the ground it has only
kinetic energy. Well, where is the potential energy that
it has at the beginning? It is totally converted to the
kinetic energy, as said in the first sentence nothing can
be destroyed or created they just change form. Thus,
our potential energy also changes its forms from
potential to the kinetic energy. In summary, energy of
the system is always constant, they can change their
forms but amount of total energy does not change.
CONSERVATION OF ENERGY THEOREM
Nothing can be destroyed or created in the universe like energy. Suppose that a ball
falls from height of 2m, it has only potential energy at the beginning, however, as it
falls it gains kinetic energy and its velocity increases. When it hits the ground it has
only kinetic energy. Well, where is the potential energy that it has at the beginning? It
is totally converted to the kinetic energy, as said in the first sentence nothing can be
destroyed or created they just change form. Thus, our potential energy also changes
its forms from potential to the kinetic energy. In summary, energy of the system is
always constant, they can change their forms but amount of total energy does not
change.
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We use
conservation of
energy in solution
of this problem.
Einitial=Efinal
Einitial=Ep+Ek=mgh+1/2mv Efinal=0
Einitial=2kg.10m/s.8m+1/2.2kg. (2m/s) Work done by friction=Einitial
Einitial=164joule
Wfriction=.N.X=0,4.2kg.10m/s.X=Ei
8. X=164joule X=20,5m
Block slides 20,5m in horizontal
Example: Find the final velocity of the box from the given picture.
We again use the conservation of energy theorem.
Einitial must be equal to the Efinal.
Einitial=Ek=1/2mv Efinal=Ek+Ep=1/2mv+mgh
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Ei=1/2.2kg.
(10m/s)
=100joule
Efinal=1/2.2kg.v+2kg.10m/s.4m=80+v
100=80+v v=25m/s
Example: Find the amount of compression of the spring if the ball does free fall from
4m and compresses the spring.
From the conservation of energy law we can find the amount of springs
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Potential Energy
Potential energy is stored energy and theenergy of position gravitational energy.
There are several forms of potentialenergy.
Kinetic Energy
Kinetic energy is motion of waves,molecules, objects, substances, and
objects.
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