Need help finding angular momentum of a particle

In summary, a 6.70 kg particle P with a position vector of magnitude 4.30 m and angle θ1 = 43.0° and a velocity vector of magnitude 3.40 m/s and angle θ2 = 32.0° experiences a force of magnitude 7.40 N and angle θ3 = 32.0°. Using the equations L = r x p and L = r x m*v, the angular momentum of the particle is calculated to be 46.0 kg·m²/s. However, without a clear description or diagram, it is uncertain if the treatment of the angles in the problem is correct. The angle θ2 = 32.0°
  • #1
Ella1777
15
0
1. At the instant of the figure, a 6.70 kg particle P has a position vector
session.quest2530192entrance1_N10034.mml
of magnitude 4.30 m and angle θ1 = 43.0° and a velocity vector
session.quest2530192entrance1_N10056.mml
of magnitude 3.40 m/s and angle θ2 = 32.0°. Force
session.quest2530192entrance1_N10078.mml
, of magnitude 7.40 N and angle θ3 = 32.0° acts on P. All three vectors lie in the xy plane. About the origin, what are the magnitude of (a) the angular momentum of the particle
2. L=r x p=r x m x v3. φ3 = Θ1 + Θ3 = 43.0º + 32.0º = 75.0º
φ2 = 270º - Θ1 - Θ2 = 270º - 43º - 32º = 195º
φ1 = Θ1 = 43.0º


r = 4.30m*(cos43.0º i + sin43.0º j)
F = 7.40N*(cos75.0º i + sin75.0º j)
v = 3.40m/s*(cos195º i + sin195º j) L = r x p = r x m*v
where L, r, p and v are vectors.
L = 4.30m * 6.70kg * 3.40m/s * (cos43.0º i + sin43º j) x (cos195º i + sin195º j)
L = 4.30m * 6.70kg * 3.40m/s * (cos43.0*sin195 - sin43.0*cos195)k
L = L = 4.30m * 6.70kg * 3.40m/s * 0.469471562 k = 45.98661738 k kg·m²/s
which has magnitude 46.0 kg·m²/s
Although this seems to be wrong what am i doing wrong?
 
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  • #2
The statement of the problem is hard to interpret. There are no images. Also, please use LaTeX for symbols.
 
  • #3
Ella1777 said:
magnitude 3.40 m/s and angle θ2 = 32.0°

Ella1777 said:
φ2 = 270º - Θ1 - Θ2 = 270º - 43º - 32
Since the images don't work, looks like you need to describe what this 32.0° angle is.
I would have guessed it meant the angle anticlockwise from the positive x axis, but that is not how you have treated it.
 
  • #4
Where does the 195° come from? It looks like v = 3.40 m/s (cos 32° i + sin 32° j).
 
  • #5
Dr Dr news said:
Where does the 195° come from? It looks like v = 3.40 m/s (cos 32° i + sin 32° j).
Ella treated the 32 degrees as though it is additional to the 43 degrees, but without the diagram (or clear description) we cannot tell if that is appropriate.
 

FAQ: Need help finding angular momentum of a particle

What is angular momentum of a particle?

Angular momentum is a measure of the rotational motion of a particle around a fixed point. It is calculated by multiplying the particle's mass, velocity, and distance from the fixed point.

How do I find the angular momentum of a particle?

The formula for calculating angular momentum is L = mvr, where L is angular momentum, m is the mass of the particle, v is the velocity, and r is the distance from the fixed point. Plug in the values and solve for L to find the angular momentum.

What units is angular momentum measured in?

Angular momentum is typically measured in units of kilogram meters squared per second (kg·m^2/s).

Can angular momentum of a particle change?

Yes, angular momentum can change if there is a change in the particle's mass, velocity, or distance from the fixed point. It can also change if an external force, such as torque, is applied to the particle.

What is the conservation of angular momentum?

The conservation of angular momentum states that the total angular momentum of a system remains constant, as long as there are no external forces acting on the system. This means that if one part of the system gains angular momentum, another part must lose an equal amount of angular momentum.

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