g In an historical movie, two knights on horseback start from rest 84.1 m apart and ride directly toward each other to do battle. Sir George's acceleration has a magnitude of 0.316 m/s2, while Sir Alfred's has a magnitude of 0.289 m/s2. Relative to Sir George's starting point, where do the knights collide?

Respuesta :

Answer:

The knights will collide at 43.854 meters relative to Sir George's starting point.

Explanation:

Let suppose that initial positions of Sir George and Sir Alfred are 0 and 84.1 meters, respectively. If both knights accelerate uniformly, then we have the following kinematic formulas:

Sir George

[tex]x_{G} = x_{G,o}+v_{o,G}\cdot t + \frac{1}{2}\cdot a_{G}\cdot t^{2}[/tex] (1)

Sir Alfred

[tex]x_{A} = x_{A,o}+v_{o,A}\cdot t + \frac{1}{2}\cdot a_{A}\cdot t^{2}[/tex] (2)

Where:

[tex]x_{G,o}[/tex], [tex]x_{A,o }[/tex] - Initial position of Sir George and Sir Alfred, measured in meters.

[tex]x_{G}[/tex], [tex]x_{A}[/tex] - Final position of Sir George and Sir Alfred, measured in meters.

[tex]v_{o,G}[/tex], [tex]v_{o,A}[/tex] - Initial velocity of Sir George and Sir Alfred, measured in meters per second.

[tex]t[/tex] - Time, measured in seconds.

[tex]a_{G}[/tex], [tex]a_{A}[/tex] - Acceleration of Sir George and Sir Alfred, measured in meters per square second.

Both knights collide when [tex]x_{G} = x_{A}[/tex], then we simplify this system of equations below:

[tex]x_{G,o} + v_{o,G}\cdot t + \frac{1}{2}\cdot a_{G}\cdot t^{2} = x_{A,o}+v_{o,A}\cdot t + \frac{1}{2}\cdot a_{A}\cdot t^{2}[/tex]

[tex](x_{A,o}-x_{G,o}) +(v_{o,A}-v_{o,G})\cdot t +\frac{1}{2}\cdot (a_{A}-a_{G})\cdot t^{2} = 0[/tex] (3)

If we know that [tex]x_{A,o} = 84.1\,m[/tex], [tex]x_{G,o} = 0\,m[/tex], [tex]v_{o,A} = 0\,\frac{m}{s}[/tex], [tex]v_{o,G} = 0\,\frac{m}{s}[/tex], [tex]a_{A} = -0.289\,\frac{m}{s^{2}}[/tex] and [tex]a_{G} = 0.316\,\frac{m}{s^{2}}[/tex], then we have the following formula:

[tex]84.1 -0.303\cdot t^{2} = 0[/tex] (4)

The time associated with collision is:

[tex]t \approx 16.660\,s[/tex]

And the point of collision is:

[tex]x_{G} = 0\,m + \left(0\,\frac{m}{s} \right)\cdot (16.660\,s)+ \frac{1}{2}\cdot \left(0.316\,\frac{m}{s^{2}} \right) \cdot (16.660\,s)^{2}[/tex]

[tex]x_{G} = 43.854\,m[/tex]

The knights will collide at 43.854 meters relative to Sir George's starting point.