Understanding Newton's Third Law: Exploring the Forces in a Collision

In summary, two hockey players, one weighing 100 kg and the other weighing 112 kg, collide with each other with a force of 50N. According to Newton's second law, their accelerations are calculated as -1.0 m/s^2 and 0.89 m/s^2 respectively. This is because the force is scaled by their masses. The net force of the system may be 0, but the force on each player is still 100N. Therefore, their accelerations can be found using the formula a = F/m, resulting in different values due to their different masses.
  • #1
hya_been
3
0
So I have a homework question that says:
A 100 kg hockey player a 112kg hockey player collide with each other each traveling with a force of 50N.

The textbook answer says that the acceleration of the 112kg is 0.89m/s^2
and the acceleration of the 100kg player is -1.0 m/s^2.

I'm confused because according to Newton's third Law there will be equal and opposite reaction forces so wouldn't they not move? Is the textbook wrong or am I?
 
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  • #2
Remember by the second law:

[tex] F = m a [/tex]

They both impart a force of 50N on each other, but the acceleration is also scaled by their masses. 50N on a 100kg person will push them farther than 50N on a 112kg person.


Imagine pushing a shopping cart with 50N. An empty shopping cart will go really far, whereas a full shopping cart will go a much shorter distance. In both instances the force is the same, but:

[tex] a = \frac{F}{m} [/tex]
 
  • #3
calculating acceleration

So you do 100/100 and 100/112 even though the total of the forces equals 0 because its 50 + -50??
 
  • #4
The net force of the entire system is 0, but the force on each player is of magnitude 100N. You can find the acceleration of each player using

[tex] a = \frac{F}{m} [/tex]. Knowing F = 100N and m = 100kg for person 1,

[tex] a = \frac{100N}{100kg} = 1.0m/s^2 [/tex]

F = 100N and m = 112kg for person 2:

[tex] a = \frac{100N}{112kg} = 0.89m/s^2 [/tex]
 
  • #5
Thank You!

Thank-you you are a saviour!
 

1. What is Newton's Third Law Problem?

Newton's Third Law, also known as the Law of Action and Reaction, states that for every action, there is an equal and opposite reaction. This means that whenever an object exerts a force on another object, the second object will exert an equal and opposite force back on the first object.

2. How does Newton's Third Law apply to everyday life?

Newton's Third Law can be observed in many everyday situations, such as when you walk. Your feet push against the ground with a certain force, and the ground pushes back with an equal force, propelling you forward. It also explains how rockets are able to launch into space by pushing hot gases out of their engines in one direction, causing the rocket to move in the opposite direction.

3. Can Newton's Third Law be violated?

No, Newton's Third Law is a fundamental law of physics and has been proven to hold true in all observed situations. It is a principle that governs the behavior of objects and forces in the universe.

4. How is Newton's Third Law related to momentum?

Newton's Third Law is closely related to the concept of momentum, which is the product of an object's mass and velocity. According to the law, when two objects interact, the forces they exert on each other are equal and opposite, causing their momenta to change in opposite directions.

5. Can two objects have equal and opposite forces acting on each other and still remain at rest?

Yes, it is possible for two objects to have equal and opposite forces acting on each other and still remain at rest. This is because the forces are cancelling each other out, resulting in a net force of 0 and no change in motion.

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