Pucks colliding at right angles

• Soniteflash
In summary, the total kinetic energy of the two-puck system is 11.0J. The magnitude of the total momentum of the two-puck system is 7.0 kg*m/s.
Soniteflash

Homework Statement

Two pucks are moving on a frictionless air table are about to collide. The 1.5 kg puck is moving directly east at 2.0 m/s. The 4.0 Kg puck is moving directly north at 1.0m/s.

What is the total kinetic energy of the two-puck system before the collision?
A. Square root of 13 J
B.5.0J
C.7.0 J
D.10J
E.11J

What is the magnitude of the total momentum of the two-puck system after the collision?
A. 1.0 kg*m/s
B. 3.5 kg*m/s
C. 5.0 kg*m/s
D. 7.0 kg*m/s
E. kg*m/s

(1/2)Mv2

P = mv

The Attempt at a Solution

F[/B]or the first question I calculated the kinetic energy of the two pucks and then used the Pythagorean Theorem since the two of them are at right angles which gave me 5 Joules.

For the second question I used the Momentum formula for both pucks. I used the Pythagorean Theorem again and got 5 kg*m/s. I am unsure about this though.

Is it an elastic or nonelastic collision?
Soniteflash said:
then used the Pythagorean Theorem since the two of them
I do not understand why you did this?
Soniteflash said:
Momentum formula for both pucks. I used the Pythagorean Theorem again and got 5 kg*m/s
If the collision is perfectly non.elastic then you're right.

Suraj M said:
If the collision is perfectly non.elastic then you're right.

Momentum would be conserved regardless of whether it was elastic or inelastic. That is why it is not necessary to specify whether or not the collision was elastic/inelastic in the problem statement.

SammyS
If the collision was elastic then the bodies wouldn't stick together, but then, well yeah you're right, question only asks about momentum of the system, not each body, sorry..

Suraj M said:
Is it an elastic or nonelastic collision?

I do not understand why you did this?

If the collision is perfectly non.elastic then you're right.

Ah, I see my error i think. Kinetic Energy is a scalar and not a vector quantity.

Soniteflash said:
Ah, I see my error i think. Kinetic Energy is a scalar and not a vector quantity.
Ok, but I'm a bit puzzled. If you did erroneously use Pythagoras, why didn't you get sqrt(13)?

Soniteflash
haruspex said:
Ok, but I'm a bit puzzled. If you did erroneously use Pythagoras, why didn't you get sqrt(13)?
Oh boy...I added instead of doing sqrt(22+32)...Can't even do wrong stuff correctly...

What is the concept of "Pucks colliding at right angles"?

The concept of "Pucks colliding at right angles" refers to the scenario where two pucks, or spherical objects, collide with each other at a 90-degree angle.

What factors determine the outcome of pucks colliding at right angles?

The outcome of pucks colliding at right angles is determined by several factors, such as the mass, velocity, and angle of collision of the pucks. The elasticity and surface properties of the pucks and the surface they collide on also play a significant role.

How does the conservation of momentum apply to pucks colliding at right angles?

The conservation of momentum states that the total momentum of a system remains constant in the absence of external forces. In the case of pucks colliding at right angles, the total momentum before and after the collision remains the same, but it may be redistributed between the two pucks.

What happens if the pucks have different masses in a collision at right angles?

If the pucks have different masses, the outcome of the collision will depend on the relative masses and velocities of the pucks. The heavier puck will have a greater momentum, and the lighter one will experience a greater change in velocity after the collision.

Can pucks collide at right angles and stick together?

Yes, pucks can collide at right angles and stick together if the collision is perfectly inelastic. In this case, the kinetic energy of the pucks is converted into other forms of energy, and the pucks move together with a common velocity after the collision.

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