Momentum vectors (add and subtract)

In summary, the conversation is about calculating vector quantities using given equations and finding the correct triangle to work with. The question is whether the calculations are correct and for help with subtracting vectors. The expert suggests reversing the direction of P2 and adding it to P1 to subtract.
  • #1
huybinhs
230
0

Homework Statement



1-9.png


I did:

P1x = 7 * 0.5 = 3.5 kg m/s ; P1y = 4*0.5 = 2 kg m/s => P1 = sqrt (3.5^2 + 2^2) = 4.03N*s

so P2 = 2.92 kg m/s ; and P3 = 2.69 kg m/s

then the question #2 is:

P1 + P2 = sqrt (4.03^2 + 2.92^2) = 4.98 kg m/s

P1 - P2 = I have no ideas.

Is my work correct? and please help with P1 - P2.

Thanks!
 
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  • #2
huybinhs said:

Homework Statement



I did:

P1x = 7 * 0.5 = 3.5 kg m/s ; P1y = 4*0.5 = 2 kg m/s => P1 = sqrt (3.5^2 + 2^2) = 4.03N*s

so P2 = 2.92 kg m/s ; and P3 = 2.69 kg m/s

then the question #2 is:

P1 + P2 = sqrt (4.03^2 + 2.92^2) = 4.98 kg m/s

P1 - P2 = I have no ideas.

Is my work correct? and please help with P1 - P2.

Thanks!

Vectors are added head to tail. For P1 + P2 you seem to be working on the wrong triangle.
I guess P1 - P2 is question #3? To subtract P2 you reverse its direction, then add as noted.
 
  • #3
Got it! Thanks! ;)
 

1. How do you calculate the total momentum of multiple objects moving in the same direction?

To calculate the total momentum of multiple objects moving in the same direction, you simply add together the individual momentums of each object. This is because momentum is a vector quantity, meaning it has both magnitude (speed) and direction. Adding the momentums of each object will give you the total momentum in the same direction.

2. Can you subtract momentum vectors?

Yes, you can subtract momentum vectors. To do so, you must first convert the momentum vectors into their x and y components, using trigonometry. Then, you can subtract the x components and the y components separately to get the resulting momentum vector.

3. What happens when two objects with opposite momentums collide?

When two objects with opposite momentums collide, their momentums cancel each other out and the total momentum of the system becomes zero. This is known as an elastic collision, where no kinetic energy is lost.

4. How does the mass of an object affect its momentum vector?

The mass of an object directly affects its momentum vector. The larger the mass of an object, the greater its momentum will be for a given velocity. This is because momentum is directly proportional to mass.

5. Can momentum vectors change direction?

Yes, momentum vectors can change direction. This can occur through a change in velocity or through a change in direction of motion. In fact, in order for an object to change direction, it must experience a net force, which causes a change in momentum and therefore a change in direction.

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