In a historical movie, two knights on horseback start from rest 86 m apart and ride directly toward each other to do battle. Sir George's acceleration has a magnitude of 0.21 m/s2, while Sir Alfred's has a magnitude of 0.26 m/s2. Relative to Sir George's starting point, where do the knights collide?

Respuesta :

Answer:

Relative to Sir George's starting point, the knights collide at a distance of 38.43 m from Sir George's starting point.

Explanation:

Let the distance covered by Sir George be [tex]S_{1}[/tex]

and the distance covered by Sir Alfred be [tex]S_{2}[/tex]

Since the knights collide, hence they must have traveled for the same amount of time just before collision

From one of the equations of motion for linear motion

[tex]S = ut + \frac{1}{2}at^{2}[/tex]

Where [tex]S[/tex] is the distance traveled

[tex]u[/tex] is the initial velocity

[tex]a[/tex] is the acceleration

and [tex]t[/tex] is the time

For Sir George,

[tex]S = S_{1}[/tex]

[tex]u[/tex] = 0 m/s (Since they start from rest)

[tex]a =[/tex]0.21 m/s²

Hence,

[tex]S = ut + \frac{1}{2}at^{2}[/tex] becomes

[tex]S_{1} = (0)t + \frac{1}{2}(0.21)t^{2}\\S_{1} = 0.105 t^{2}\\[/tex]

[tex]t^{2} = \frac{S_{1}}{0.105}[/tex]

Now, for Sir Alfred

[tex]S = S_{2}[/tex]

[tex]u[/tex] = 0 m/s (Since they start from rest)

[tex]a =[/tex]0.26 m/s²

Hence,

[tex]S = ut + \frac{1}{2}at^{2}[/tex] becomes

[tex]S_{2} = (0)t + \frac{1}{2}(0.26)t^{2}\\S_{2} = 0.13 t^{2}\\[/tex]

[tex]t^{2} = \frac{S_{2}}{0.13}[/tex]

Since, they traveled for the same time, [tex]t[/tex] just before collision, we can write

[tex]\frac{S_{1}}{0.105}= \frac{S_{2}}{0.13}[/tex]

Since, the two nights are 86 m apart, that is, the sum of the distances covered by the knights just before collision is 86 m. Then we can write that

[tex]S_{1} + S_{2} = 86[/tex] m

Then, [tex]S_{2} = 86 - S_{1}[/tex]

Then,

[tex]\frac{S_{1}}{0.105}= \frac{S_{2}}{0.13}[/tex] becomes

[tex]\frac{S_{1}}{0.105}= \frac{86 -S_{1}}{0.13}[/tex]

[tex]0.13{S_{1}}= 0.105({86 -S_{1}})\\0.13{S_{1}}= 9.03 - 0.105S_{1}}\\0.13{S_{1}} + 0.105S_{1}}= 9.03 \\0.235{S_{1}} = 9.03\\{S_{1}} =\frac{9.03}{0.235}[/tex]

[tex]S_{1} = 38.43[/tex] m

∴ Sir George covered a distance of 38.43 m just before collision.

Hence, relative to Sir George's starting point, the knights collide at a distance of 38.43 m from Sir George's starting point.