The Motion of the Center of Mass

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SUMMARY

The discussion focuses on a projectile motion problem involving an explosion at the peak of its trajectory. A projectile is launched with an initial speed \( v_0 \) at an angle \( \theta \). Upon explosion, the conservation of momentum is applied to determine the velocities of the two resulting pieces. The first piece lands a horizontal distance \( D \) from the explosion point, and the discussion seeks to find the maximum height and landing position of the second piece in terms of \( v_0 \), \( \theta \), \( D \), and time \( t \).

PREREQUISITES
  • Understanding of projectile motion principles
  • Knowledge of conservation of momentum
  • Familiarity with kinematic equations
  • Ability to analyze two-dimensional motion
NEXT STEPS
  • Study the derivation of projectile motion equations
  • Learn about conservation of momentum in two dimensions
  • Explore the effects of explosions on projectile trajectories
  • Investigate the use of vector components in motion analysis
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Students studying physics, particularly those focusing on mechanics and projectile motion, as well as educators seeking to enhance their understanding of conservation laws in dynamic systems.

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Homework Statement



A projectile is launched with speed v0 at an angle theta with respect to the horizontal. At the peak of its motion, it explodes into two pieces of equal mass, which continue to move in the original plane of motion. One piece strikes the ground a horizontal distance D further from the launch point than the point directly below the explosion at time (t < v0 sin(theta) / g) after the explosion. How high does the other piece go? Where does the other piece land? Answer in terms of v0, theta, D, and t.

Homework Equations



Conservation of momentum
<br /> v = v_0 + a t<br />
x = x_0 + v_0 t + (1/2) a t^2
<br /> v^2 = v_0^2 + 2 a \Delta x<br />
Others?

The Attempt at a Solution



I started out by drawing a picture of the particles. I assume since the first particle hits the ground at less than half of the time of flight, it must have been directed downward. I set up conservation of momentum formulae for both the x and y directions:
2 v_0 cos\theta = v_1 cos\theta_1 + v_2 cos\theta_2
0 = v_1 sin\theta_1 + v_2 sin\theta_2
Also:
v_1 cos\theta_1 = \frac{D}{t}
I'm not sure where to go from here. All attempts seem to lead to dead ends. Any help is appreciated. Thanks!
 
Last edited:
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What do you know about the velocity in the x direction and in the y direction? If you have velocity and distance covered by the object, what else do you know about that object?

You know how fast the object is going in the x direction and how far it goes, so you can solve for time correct? Now, why was the ball only allowed to go as far as it did?
 

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