You are in your car driving on a highway at 23 m/s when you glance in the passenger-side mirror (a convex mirror with radius of curvature 150 cm) and notice a truck approaching. If the image of the truck is approaching the vertex of the mirror at a speed of 2.0 m/s when the truck is 2.0 m away, what is the speed of the truck relative to the highway?

Respuesta :

Answer:

v = 26. 88 m/s +23 m/s

Explanation:

u = 23 m/s, r = 150 cm, u₁ = 2.0 m/s, s =2.0 m

[tex]\frac{1}{s} +\frac{1}{s'} = \frac{2}{R}[/tex]

[tex]\frac{1}{2.0 m} +\frac{1}{s'} = \frac{2}{1.50 m}[/tex]

Solve s'

[tex]\frac{1}{s'}  = \frac{2}{1.50 m} - \frac{1}{2.0 m}[/tex]

[tex]\frac{1}{s'} =  1.833 m[/tex]

[tex]s' = - 0.545 m[/tex]

To determine the speed of the trick to the highway

[tex]\frac{ds}{dt}= \frac{s^2* \frac{ds}{dt}}{s' ^2} =\frac{2.0 ^2m * 2.0 m/s}{0.545^2m}[/tex]

[tex]\frac{ds}{dt} = 26.88 m/s[/tex]

Now to determine the velocity highway is going to be

v = ds/dt + u

v = 26. 88 m/s +23 m/s