Newton's third law of motion help

In summary, according to Newton's laws of motion, the correct answer is E - none of the above is true according to the third law. This is because in all of the scenarios given, there is not an equal and opposite force being exerted, which is a key principle of Newton's 3rd law. For example, in scenario D, the astronauts throwing a ball back and forth, although the distance between them remains constant, the force exerted on the ball is not equal and opposite to the force exerted on the astronauts. Therefore, the distance between them will not increase due to a force between the catcher and thrower, but rather due to the force exerted on the ball.
  • #1
jehan4141
91
0
Hello! My question is about Newton's 3rd law:

Which one of the following is true, according to Newton's laws of motion? Ignore friction.

a. an SUV hits a stationary motorcycle. Since it is stationary, the motorcycle sustains a greater force than the SUV does
b. a semitrailer truck crashes all the way through a wall. since the wall collapses, the wall sustains a greater force than the truck does.
c. sam (18 years old) and his sister (9 years old) go ice skating. they push off against each other and fly apart. sam flies off with greater acceleration.
d. two astronauts on a space walk are throwing a ball back and forth ebtween each other. in this game of catch the distance ebtween them remains constant
e. none of the above is true, according to the third law.

I know that the answer is E, that none of the above is true, but I do not understand what D is saying. How does E apply to the third law?

Thank you so much in advance! :)
 
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  • #2
Ohhh okay I think I may have gotten it. Is it because as you throw a ball, you exert a force on the ball, in the direction of the catcher. Thus, there's an equal and opposite force placed upon you (the thrower). So you are propelled further and further from the other person (the catcher)?
 
  • #3
In throwing and catching the ball, you exert a force on the ball. Because of the opposite force from the ball, the distance will increase (not because of a force between the catcher and thrower)
 
  • #4
Thank you! :)))
 
  • #5


Hello! According to Newton's third law of motion, for every action there is an equal and opposite reaction. This means that in all of the situations described above, there is an equal and opposite force acting on each object involved.

In option A, the SUV and motorcycle are exerting equal and opposite forces on each other upon impact. This is because the SUV is exerting a force on the motorcycle, causing it to move, and the motorcycle is also exerting a force on the SUV in the opposite direction.

In option B, the truck and the wall are also exerting equal and opposite forces on each other. The truck is exerting a force on the wall, causing it to collapse, and the wall is exerting an equal and opposite force on the truck, causing it to slow down and eventually stop.

In option C, Sam and his sister are also exerting equal and opposite forces on each other as they push off against each other while ice skating. This is why they fly apart with equal acceleration.

In option D, the astronauts throwing a ball back and forth are also experiencing equal and opposite forces. Each time one astronaut throws the ball to the other, the ball exerts a force on the astronaut, and the astronaut exerts an equal and opposite force on the ball. This is why the distance between them remains constant.

Therefore, E is the correct answer because all of the options described do follow Newton's third law of motion. I hope this helps to clarify the concept for you!
 

FAQ: Newton's third law of motion help

What is Newton's third law of motion?

Newton's third law of motion states that for every action, there is an equal and opposite reaction. This means that when an object exerts a force on another object, the second object will exert an equal force in the opposite direction on the first object.

How does Newton's third law apply to everyday situations?

An everyday example of Newton's third law is walking. When a person takes a step forward, they push backwards on the ground with their foot. The ground then exerts an equal and opposite force on the person, propelling them forward.

Does Newton's third law only apply to objects in motion?

No, Newton's third law applies to all objects, whether they are in motion or not. Even if an object is at rest, it is still exerting a force on the surface it is resting on, and the surface is exerting an equal and opposite force on the object.

Can Newton's third law be violated?

No, Newton's third law is a fundamental law of physics and cannot be violated. However, there are some situations where it may appear to be violated, such as when objects are in contact for a very short period of time or when the forces are not acting on the same objects.

How did Newton come up with his third law of motion?

Newton's third law of motion is a result of his second law of motion, which states that force is equal to mass times acceleration. By combining this with his first law of motion, which states that an object will remain at rest or in motion at a constant velocity unless acted upon by a force, Newton was able to deduce his third law.

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