# How Do Newton's Third Law and Force Calculations Apply to Hockey Players on Ice?

• VidsEpic
In summary: An astronaut in space may push off with his legs against one end of the spaceship with 100 N force. But that does not mean that the spaceship applies 0 force to the astronaut. On the contrary, the spaceship applies 100N of force to the astronaut. There is no difference between "apply" and "push" here.
VidsEpic

## Homework Statement

two hockey players are standing on ice. Player A is 100kg and player B is 112kg, Player A pushes B with 40N and player B pushes A with 50N.

what are the action/reaction forces?
what are the accelerations?

F = ma

## The Attempt at a Solution

player A has a force of 50N on him plus the reaction from his own force of 40N making 90N left

90N on each player in opposite directions, 90/100 = 0.9 m/s^2 and 90 /112 = 0.8 m/s ^2 in other direcctionPlease help me!

VidsEpic said:

## Homework Statement

two hockey players are standing on ice. Player A is 100kg and player B is 112kg, Player A pushes B with 40N and player B pushes A with 50N.

what are the action/reaction forces?
what are the accelerations?

F = ma

## The Attempt at a Solution

player A has a force of 50N on him plus the reaction from his own force of 40N making 90N left

90N on each player in opposite directions, 90/100 = 0.9 m/s^2 and 90 /112 = 0.8 m/s ^2 in other direcction

Looks fine.
Where do you need help?

Is this correct?

The diagram looks like this:http://i.imgur.com/LP6NfNw.jpgsome people are telling me that it is 10N left on the 100kg object?

Is it correct that I consider on each object the force of its own reaction + the force applied to it so that on 100kg I have 90N left and on 112kg I have 90N right?

VidsEpic said:
Is it correct that I consider on each object the force of its own reaction + the force applied to it so that on 100kg I have 90N left and on 112kg I have 90N right?
I would interpret the problem statement in that way, yes.

Please don't write PMs related to homework threads, they are just annoying.

VidsEpic said:

## Homework Statement

two hockey players are standing on ice. Player A is 100kg and player B is 112kg, Player A pushes B with 40N and player B pushes A with 50N.
This is a poor question, in my view. What does it mean that A applies 40 N of force to B and B applies 50 N to A? How? They will always apply the same magnitude of force to each other - even if one pushes harder than the other.

AM

The players are extended bodies, and push each other at different points. See picture.

ehild

#### Attachments

• pushing.JPG
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ehild said:
The players are extended bodies, and push each other at different points. See picture.

ehild
Ok. But that does not mean that they push each other with different magnitudes of force.

An astronaut in space may push off with his legs against one end of the spaceship with 100 N force. But that does not mean that the spaceship applies 0 force to the astronaut. On the contrary, the spaceship applies 100N of force to the astronaut. There is no difference between "apply" and "push" here.

AM

## What is Newton's Third Law?

Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on another object, the second object exerts a force back on the first object that is equal in magnitude but opposite in direction.

## How does Newton's Third Law relate to everyday life?

Newton's Third Law can be observed in many aspects of everyday life. For example, when you walk, your foot exerts a force on the ground, and the ground exerts an equal and opposite force back on your foot, propelling you forward. Another example is when you blow up a balloon, the air inside exerts a force on the walls of the balloon, and the walls of the balloon exert an equal and opposite force back on the air, causing the balloon to expand.

## Can Newton's Third Law be violated?

No, Newton's Third Law is a fundamental law of physics and cannot be violated. It is a universal principle that applies to all objects in the universe.

## How does Newton's Third Law apply to motion?

Newton's Third Law is closely related to Newton's First Law of Motion, also known as the Law of Inertia. According to Newton's First Law, 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. When an object is in motion, it is constantly experiencing an equal and opposite force from another object, which allows it to maintain its motion.

## What is the difference between action and reaction forces in Newton's Third Law?

The action force is the force exerted by one object on another, while the reaction force is the force exerted by the second object back on the first object. These forces are equal in magnitude but opposite in direction, and they act on different objects.

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