Newtons law of motion type of question

In summary, if the forces are opposite of each other, then the net force is negative. If the forces are in the same direction, then the net force is positive.
  • #1
Kurwa
4
0
Two forces, of magnitude 10N and 4N, are applied to an object. The relative direction of the forces is unknown. The net force acting on the object __________.

Check all that apply ?

a) cannot be equal to 5N
b)cannot be equal to 10N
c)cannot be directed the same way as the force of 10N
d) must be greater than 10N

Thanks =]
 
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  • #2
Welcome to PF!

Hi Kurwa ! Welcome to PF! :wink:

Show us how far you get, and where you're stuck, and then we'll know how to help! :smile:
 
  • #3


ok well first i drew a 2 different systems (dots)

first dot- both forces to the right i.e 10N and 4N 0-----> 14N
second dot- forces opposite of each other 10N <--0-> 4N = 6N <--

now as you can see (a and b) are true

c) must be true because the net force can act in the same way as the 10N was (second dot)

d) which i totally don't understand because if the two forces are opposite of each other it holds false but if the two forces are in the same direction it holds true ??

soo that's why I am getting them wrong after 3 attempts ?
 
  • #4


Kurwa said:
ok well first i drew a 2 different systems (dots)

first dot- both forces to the right i.e 10N and 4N 0-----> 14N
second dot- forces opposite of each other 10N <--0-> 4N = 6N <--

now as you can see (a and b) are true

c) must be true because the net force can act in the same way as the 10N was (second dot)

d) which i totally don't understand because if the two forces are opposite of each other it holds false but if the two forces are in the same direction it holds true ??

soo that's why I am getting them wrong after 3 attempts ?


For d.) If the statement is false in one case and true in another, what does that tell you about the statement overall?

for a and b.) Try breaking the 2 forces into x and y components (remember the forces don't have to be applied solely on the axes).
 
  • #5


Hey NBA- I don't understand your post- ?
 
  • #6
Kurwa said:
Hey NBA- I don't understand your post- ?

NBAJam100 :smile: means that you've assumed that the forces must be in the same or opposite directions (left or right), but in fact they can be at any angle to each other.

(and your "c) must be true" contradicts your own reasoning :wink:)
 
  • #7


Kurwa said:
ok well first i drew a 2 different systems (dots)

first dot- both forces to the right i.e 10N and 4N 0-----> 14N
second dot- forces opposite of each other 10N <--0-> 4N = 6N <--

now as you can see (a and b) are true

c) must be true because the net force can act in the same way as the 10N was (second dot)

d) which i totally don't understand because if the two forces are opposite of each other it holds false but if the two forces are in the same direction it holds true ??

soo that's why I am getting them wrong after 3 attempts ?
Try making one of the dots directly up and one to the side, and check all of the statements again - the question didn't say that they're going to be in the same direction.

:smile:
 

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

Newton's three laws of motion are:
1. 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.
2. Force is equal to mass times acceleration.
3. For every action, there is an equal and opposite reaction.

2. How do Newton's laws of motion affect everyday life?

Newton's laws of motion explain how objects move and interact with each other. They can be seen in everyday activities such as walking, driving a car, and playing sports. These laws also play a role in the design and function of machines and structures.

3. What is an example of Newton's first law of motion?

An example of Newton's first law, also known as the law of inertia, is a hockey puck sliding across the ice. The puck will continue to move in a straight line at a constant speed unless acted upon by an external force, such as a player's stick or friction from the ice.

4. How is Newton's second law of motion used in science and engineering?

Newton's second law, also known as the law of acceleration, is used to calculate the force needed to move an object of a certain mass at a certain acceleration. This law is essential in fields such as physics, engineering, and mechanics.

5. Can Newton's third law of motion be observed in space?

Yes, Newton's third law, also known as the law of action and reaction, can be observed in space. For example, when a rocket is launched, the force of the escaping gas propels the rocket in the opposite direction with an equal amount of force. This law explains how objects move and interact in the vacuum of space.

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