I walk 1km up the hill at 4km/h and 1km down the hill at 6km/h.

What is my mean speed?

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- May 8th 2006, 01:11 PMNatasha1Mean speed
I walk 1km up the hill at 4km/h and 1km down the hill at 6km/h.

What is my mean speed? - May 8th 2006, 01:43 PMtopsquarkQuote:

Originally Posted by**Natasha1**

$\displaystyle t_1 = \frac{x_1}{v_1}=\frac{1 \, km}{4 \, km/hr}=\frac{1}{4} \, hr$

$\displaystyle t_2 = \frac{x_2}{v_2}=\frac{1 \, km}{6 \, km/hr}=\frac{1}{6} \, hr$

$\displaystyle t = t_1+t_2 = \frac{1}{4} \, hr+\frac{1}{6} \, hr =\frac{5}{12} \, hr \approx 0.416667 \, hr$

So the average speed for the round trip will be:

$\displaystyle v = \frac{x}{t}=\frac{2 \, km}{0.416667 \, hr}=4.8 \, km/hr$

-Dan