Exploring Momentum Conservation Using a Pendulum

In summary: Newton's cradle, exhibits two of the conservation laws: conservation of momentum, as we easily see by pulling one ball to the side and releasing, and conservation of kinetic energy in an Inelastic collision, which we can observe by pulling up two adjacent balls to the side at once and releasing. Rather than one ball moving at twice the velocity, which would still satisfy the conservation of momentum, two balls swing. Try use the equations for the conversation of kinetic energy in inelastic collisions to show why this must occur.Newton's Cradle exhibits two of the conservation laws: Conservation of momentum, as we easily see by pulling one ball to the side and releasing, and Conservation of Kinetic Energy in an Inelastic collision
  • #1
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We were told to make our own project, i chose to base mine on the conservation of momentum and used the pendulum.
Though I am kind of stuck, i need more things to write about and more equations i can calculate using the pedulum.

all i have so far is
E=mgh
H1=0.145m (90dgrs)
M=0.045kg

E=0.045x9.8x0.145
E=0.063945 J

1/m(v^2)
v^2=0.063945x2/0.045
v=1.685ms^-2

so that's the velocity of my first ball on 90 degrees.
and when that ball hit the ball on the other side went up 0.11m (11cm)
so;
H2=0.11
m=0.045

done same equations as before and got v=1.468ms^-2

so now i can only prove that the velocity changes to 1.468 from 1.685.
and that its inelastic because it changes, if you know what i mean.
i need more things that i can work with, more things i can try and find out with the pendulum. and how can i find out how long it will take before the pendulum will come to rest.
help anyone?
 
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  • #2
Newton's Cradle exhibits two of the conservation laws: Conservation of momentum, as we easily see by pulling one ball to the side and releasing, and Conservation of Kinetic Energy in an Inelastic collision, which we can observe by pulling up two adjacent balls to the side at once and releasing. Rather than one ball moving at twice the velocity, which would still satisfy the conservation of momentum, two balls swing. Try use the equations for the conversation of kinetic energy in inelastic collisions to show why this must occur.
 
  • #3
Gib Z said:
Newton's Cradle exhibits two of the conservation laws: Conservation of momentum, as we easily see by pulling one ball to the side and releasing, and Conservation of Kinetic Energy in an Inelastic collision, which we can observe by pulling up two adjacent balls to the side at once and releasing. Rather than one ball moving at twice the velocity, which would still satisfy the conservation of momentum, two balls swing. Try use the equations for the conversation of kinetic energy in inelastic collisions to show why this must occur.

So for kinetic energy.
The first ball.
Ek=0.5x0.045x1.685^2
Ek=0.063833

The second ball.
Ek=0.5x0.045x1.46833
Ek=0.0451

but i still don't know how i can find the time to when the cradle comes to rest.
 
  • #4
help please i need to find out how long it will take before the cradle comes to a rest.
will this help?
T= 2pi(sqrtL/g)
 
  • #5
It never stops in the ideal model. Energy is lost in the real model in the collisions, then it stops.
 
  • #6
Gregg said:
It never stops in the ideal model. Energy is lost in the real model in the collisions, then it stops.

Yes i know because its inelastic.
Though i need to find out how long it will take for an inelastic model to come to rest.
 
  • #7
It is not simple to find out when the cradle will stop. Do some more observations. From the difference of the initial and final height you can follow the lost energy at each collision. It is difficult to predict how the energy will change in time, but you can plot the heights in terms of the number of collisions, and you can extrapolate the curve after a few swings to zero energy. ehild
 

What is momentum conservation?

Momentum conservation is a fundamental law of physics that states that the total momentum of a system remains constant, unless acted upon by an external force. This means that in any interaction or process, the total momentum before and after the event remains the same.

How is a pendulum used to explore momentum conservation?

A pendulum is a simple mechanical system that demonstrates the principle of momentum conservation. As the pendulum swings back and forth, the mass at the end of the pendulum experiences changes in velocity and direction, but the total momentum of the system remains constant.

What factors affect the momentum of a pendulum?

The momentum of a pendulum is affected by the mass of the pendulum, the length of the pendulum, and the initial angle at which it is released. The greater the mass and length of the pendulum, the greater the momentum. The initial angle also plays a role in determining the momentum of the pendulum.

How does friction affect momentum conservation in a pendulum?

Friction can cause a decrease in the total momentum of a pendulum system. As the pendulum swings, frictional forces act upon it, converting some of its kinetic energy into thermal energy. This results in a decrease in the total momentum of the system over time.

What real-life applications does momentum conservation have?

Momentum conservation has numerous real-life applications, including in sports such as billiards and bowling, where the laws of conservation of momentum are used to predict the motion of objects. It is also important in understanding and designing transportation systems, such as cars and airplanes, as well as in the fields of engineering, robotics, and space exploration.

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