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DATA and OBSERVATIONS
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TABLE 1. Getting the Initial Velocity of the Steel Ball, Ballistic Method
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mass of the steel ball,
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| TRIAL | Angle |
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| 1 |
25 o |
Initial height of the pendulum
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| 2 |
25 o |
Final height of the pendulum
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| 3 |
25 o |
Increase in height,
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| 4 |
25 o |
Velocity of the steel ball and the pendulum right after collision,
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| 5 |
25 o |
Velocity of the pendulum before collision
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Average angle: 25 o |
Velocity of the steel ball before collision,
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| TABLE 2. Getting the Initial Velocity of the Steel Ball, Trajectory Method | |||
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Gravitational constant, g = 980 cm/s2
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| TRIAL | Horizontal Distance, |
Height from the reference point to the ground
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| 1 | 153.10 cm | ||
| 2 | 154.20 cm | ||
| 3 | 152.60 cm |
Velocity of the steel ball before collision, |
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| 4 | 153.50 cm | ||
| 5 | 154.30 cm | ||
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Average
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| TABLE 3. Determining the Percentage Difference | |
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Percentage Difference , % diff= |
Percent difference = 2.17 % |
GUIDE QUESTIONS
1. Suppose a ball with half the mass is used and is projected out of the launcher with the same speed. How
does the increase in height of the system now compared with that when the original ball was used? Defend
your answer.
If we used a ball with half mass with the same initial speed, the resulting increase in height will be smaller than the original mass but not exactly half the original increase in height. The height when half of the mass is used is less than the increase in height when the original ball was used.
Considering the results given on the data sheet:
m1 = 65.875/2 = 32.9375 g
m2 = 238.7 g
v1 = 498.88 cm/s yn = 1.867 cm < 5.4 cm
v1 = ( 2gy)(m1 + m2)/ m1
2. Suppose the launcher is positioned higher above the table top. How does this change affect the computed
initial speed of the ball? Defend your answer.
When the launcher is positioned higher above the table top, the initial speed of
the ball will still be the same because as we can recall the lessons in kinematics,
the horizontal velocity of the projectile is always constant, Thus, whenever the
height increases, the range also increases proportionally making the initial
velocity of the ball the same which can be computed using the formula:
3. A 50 gram bullet is fired horizontally into a 5 kg block of wood suspended by a long cord. The bullet sticks in
the block. Determine the velocity of the bullet if the inelastic collision causes the block to swing 0.10 m
above its initial.
m1 = 0.005 kg 
m2 = 5 kg
y = 0.10 m
V1 = (0.005 + 5 kg) 2(9.8) (0.1m)
0.005 kg
V1 = 1,401.4 m/s
ANALYSIS
1. Which method (ballistic method or trajectory method) is more accurate in determining the initial speed of
the ball. Defend your answer.
The ballistic method is more accurate in finding the initial speed of the ball
because unlike the trajectory method, we do not need to find the horizontal
displacement of the ball. The horizontal displacement of the ball (x) is also
not accurate since there could always be a small margin of error if you
measure it with the use of a meter stick. Using the ballistic method, we only
need to determine the increase in the height of the pendulum, and compute
the intial velocity using the equation:
Using this formula of the ballistic method, we can have a more accurate result
than using the trajectory method.
2. In Part 1 of the experiment, is the total momentum of the system conserved? Explain.
Yes, the total momentum of the system is conserved. In part 1 (Ballistic
method), the ballistic method is an example of an inelastic collision. The
law of conservation states that in an inelastic collision, the total momentum
of the system is always conserved.
3. In Part 1 of the experiment, when is the total energy of the system not conserved? When is the total
energy of the system conserved?
The total energy of the system is conserved during the collision. The total
momentum before an inelastic collision is the same as after the collision.
Since what is asked is the total energy not the total kinetic energy, the total
energy is conserved because the total kinetic energy before and after the
inelastic collision is different. Of course this does not mean that total energy
has not been conserved, rather the energy has been transformed into another
type of energy.
CONCLUSION
1. What causes the total momentum of the system to change?
Momentum, like mass, is also a conserved quantity, and there is a law that
states that "the momentum in an isolated system is constant". This law is the
law of conservation of momentum. The law of conservation of momentum is
very useful in the analysis of collisions and explosions as it can be used to
calculate the velocities of a body or bodies before and after the collision.
Since momentum is a conserved quantity, external forces such as air resis-
tance are the one that causes the total momentum of a system to change.
2. When the total momentum of the system is conserved, is the total energy of the system conserved
as well? Explain.
Yes, both the energy and the momentum of the system are conserved. In an
elastic collision, both kinetic energy and momentum is conserved. In an
inelastic collision, the total momentum is also conserved but the total
kinetic energy is not. An inelastic collision is usually accompanied by defor-
mation of one or both bodies. This requires energy thus; the total energy
is conserved but not necessarily the kinetic energy.
3. Is the total momentum of the system conserved in all kinds of collisions? Explain.
Yes, the total momentum in all kinds of collisions is conserved. In an elastic
collision, both energy and momentum is conserved. In an inelastic collision,
the total momentum is conserved but total kinetic energy is not conserved
the kinetic energy is transformed into other kinds of energy. Also, the law of
conservation of momentum states that the total momentum of the system
before collision is equal to the total momentum of the system after collision.
hoy brad, alam ko late na to pero mali sagot mo sa velocity
ReplyDeletedapat .05kg hindi .005 haha :p
hoy ka din. di na pwede balikan ang nakalipas, okay?
Deletebitter ka. move on din pag may time!!!
Delete