A car travels from point A to point B, moving in the same direction but with a non-constant speed. The first half of the distance, the car travels with a speed v 1 â.The remaining part of the way, the car travels half the time with a speed v2 ââand half the time with a speed v3 ââ . What is the average speed over the entire journey?

Respuesta :

Answer:

Explanation:

From A to B

distance traveled with velocity [tex] v_1[/tex]  in time [tex]t_1[/tex]

[tex]\frac{d}{2}=v_1t_1----1[/tex]

from B to C

distance traveled is 0.5 d with [tex]v_2[/tex]  and [tex]v_3[/tex]  velocity for half-half time

[tex]\frac{d}{2}=\frac{v_2t_2}{2}+\frac{v_3t_3}{2}----2[/tex]

divide 1 and 2 we get

[tex]\frac{1}{1}=\frac{2v_1t_1}{v_2t_2+v_3t_3}[/tex]

[tex]\frac{t_1}{t_2}=\frac{v_2+v_3}{2v_1}[/tex]

Now average velocity is given by

[tex]v_{avg}=\frac{d}{t_1+t_2}[/tex]

taking [tex]t_1[/tex]  common

[tex]v_{avg}=\frac{2v_1t_1}{t_1(1+\frac{t_2}{t_1})}[/tex]

[tex]v_{avg}=\frac{2v_1}{1+\frac{2v_1}{v_2+v_3}}[/tex]

[tex]v_{avg}=\frac{2v_1(v_2+v_3)}{2v_1+v_2+v_3}[/tex]  

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