Newton's Laws/Conservation of Momentum/Kinetic Energy

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lucidion24
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Hello, I have a mid-term for Physical Science due on Wednesday. It's a 5 question take-home mid-term. Now I know these questions may be trivial to some of you, but I am in college purely for a business degree and have no use for physics. I'm primarily just looking to pass this course. Now, don't think that I don't pay attention in class, because I do. I am a student with a 3.7GPA but I just cannot comprehend the way my instructor is teaching this class.. Anyway, here are the questions. Help with them are greatly appreciated.

1. A 2.5 kg bowling ball slides across the floor with a velocity of 4.0 m/s. The bowling ball has a kinetic energy and momentum of: _______ Joules and ________ kg*m/s

2. If you were to lift the same bowling ball to a height of 4 m above the floor, its potential energy would increase by _______ Joules

3. A freight train rolls along a track with a speed of 10 m/s. If it's speed were increased to 30 m/s, its kinetic energy would be increased by a factor of _______

4. A 100,000kg railroad car traveling at 5 m/s collides with a stationary railroad car of the same mass. If the two cars couple together after the collision, because momentum will be conserved, they will have a speed of ________ m/s

5. The acceleration of gravity at the surface of the Earth is 9.8 m/s^2. If the mass of the Earth could be doubled keeping its radius the same, the acceleration of gravity would then be _________ m/s^2

Homework Equations



If I knew, I probably wouldn't be asking..

The Attempt at a Solution



Once again, if I even knew were to begin, I might have an idea of what these solutions will be.

I am not here for an easy 100.. I would like to be able to understand what is taught. If someone could explain these questions to me in a means in which I would be able to understand, I would appreciate it very much. Time is limited, my exam is due 6PM Tomorrow CST. Thank you for your time, understanding, and help!
 
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  • #2
I believe that it's against our rules to help you with this take-home test.
 
  • #3
SammyS said:
I believe that it's against our rules to help you with this take-home test.

What is the point of homework help if it's against the rules to help with homework? That's a puzzling concept.. Oh well..
 
  • #4
re 1.Try to find the formulae for kinetic energy and momentum.
re 2. Try using conservation of energy principle.
re 3. use formula of KE
re 4. use conservation of momentum.
 
  • #5
lucidion24 said:
What is the point of homework help if it's against the rules to help with homework? That's a puzzling concept.. Oh well..

Re-read the Rules link at the top of the page. You agreed to those rules when you joined the PF. The Homework Help rules are quite clear.

This additional thread will help you understand why we have the HH rules that we do.

https://www.physicsforums.com/showthread.php?t=373889

This thread is locked. Do not post exam questions here in the future.

berkeman
PF Mentor
 
Last edited:

Related to Newton's Laws/Conservation of Momentum/Kinetic Energy

1. What are Newton's three laws of motion?

Newton's first law states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity, unless acted upon by an external force. Newton's second law states that the force on an object is equal to its mass multiplied by its acceleration. Newton's third law states that for every action, there is an equal and opposite reaction.

2. How do these laws relate to conservation of momentum?

Conservation of momentum is a consequence of Newton's third law. When two objects interact, they exert equal and opposite forces on each other. This means that the total momentum of the system (the two objects) remains constant. This is known as the law of conservation of momentum.

3. How does kinetic energy relate to these laws?

According to Newton's second law, the force on an object is equal to its mass multiplied by its acceleration. When an object is in motion, it has kinetic energy, which is the energy of motion. This means that the greater the mass and velocity of an object, the more kinetic energy it has.

4. Can these laws be broken or changed?

No, these laws are fundamental principles of physics and have been repeatedly tested and proven to be true. However, they may not always seem to apply in certain situations, such as very small or very fast objects, but they still hold true at a larger scale.

5. How do these laws impact our daily lives?

Newton's laws of motion and the concept of conservation of momentum and energy are crucial in understanding the physical world around us. They are applied in various fields, such as engineering, transportation, and sports. For example, the design of cars and planes relies on these laws to ensure safe and efficient movement. In sports, athletes utilize these principles to enhance their performance, such as in the long jump or javelin throw.

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