To tackle this problem, we need to apply the principles of momentum conservation in a two-dimensional collision scenario. Let’s break it down step by step, starting with the vector diagram and moving through the equations and calculations.
Visualizing the Collision
In a collision between two billiard balls, we can represent their velocities as vectors. Since ball A is moving and ball B is stationary, we can illustrate this with a vector diagram:
- Draw a horizontal line to represent the initial velocity of ball A (4.2 m/s).
- From the tip of this vector, draw a line at a 25-degree angle to the left to represent the direction of ball A after the collision.
- From the origin, draw another line at a 65-degree angle to the right to represent the direction of ball B after the collision.
Label the vectors as follows:
- Vector A_initial (4.2 m/s)
- Vector A_final (after collision, at 25 degrees)
- Vector B_final (after collision, at 65 degrees)
Applying the Conservation of Momentum
The law of conservation of momentum states that the total momentum before the collision equals the total momentum after the collision. For our scenario, we can express this mathematically.
Momentum Equation
Let’s denote:
- m = mass of each ball = 0.165 kg
- v_A_initial = initial velocity of ball A = 4.2 m/s
- v_A_final = final velocity of ball A
- v_B_final = final velocity of ball B
The equation for conservation of momentum in the x-direction (horizontal) and y-direction (vertical) can be written as:
In the x-direction:
m * v_A_initial = m * v_A_final * cos(25°) + m * v_B_final * cos(65°)
In the y-direction:
0 = m * v_A_final * sin(25°) - m * v_B_final * sin(65°)
Calculating Final Velocities
Now, we can simplify these equations. Since the masses are the same, we can cancel them out:
Horizontal Momentum Equation
4.2 = v_A_final * cos(25°) + v_B_final * cos(65°)
Vertical Momentum Equation
0 = v_A_final * sin(25°) - v_B_final * sin(65°)
From the vertical equation, we can express v_A_final in terms of v_B_final:
v_A_final * sin(25°) = v_B_final * sin(65°)
v_A_final = (v_B_final * sin(65°)) / sin(25°)
Now, substitute this expression for v_A_final into the horizontal momentum equation:
4.2 = ((v_B_final * sin(65°)) / sin(25°)) * cos(25°) + v_B_final * cos(65°
Now, let’s solve for v_B_final:
4.2 = v_B_final * ( (sin(65°) * cos(25°) / sin(25°)) + cos(65°) )
Calculating the trigonometric values:
- sin(25°) ≈ 0.4226
- cos(25°) ≈ 0.9063
- sin(65°) ≈ 0.9063
- cos(65°) ≈ 0.4226
Substituting these values into the equation:
4.2 = v_B_final * ( (0.9063 * 0.9063 / 0.4226) + 0.4226 )
Calculating the terms:
4.2 = v_B_final * ( 6.049 + 0.4226 )
4.2 = v_B_final * 6.4716
Now, solving for v_B_final:
v_B_final ≈ 4.2 / 6.4716 ≈ 0.649 m/s
Now, substituting v_B_final back to find v_A_final:
v_A_final = (0.649 * sin(65°)) / sin(25°)
v_A_final = (0.649 * 0.9063) / 0.4226 ≈ 1.4 m/s
Final Results
After the collision:
- Ball A moves at approximately 1.4 m/s at an angle of 25 degrees to the left.
- Ball B moves at approximately 0.649 m/s at an angle of 65 degrees to the right.
This analysis illustrates how momentum is conserved in a two-dimensional collision, allowing us to determine the final velocities of both balls after impact.