- Thread starter
- #1

#### karush

##### Well-known member

- Jan 31, 2012

- 2,724

2-3 You normally drive on the freeway between San Diego and Los Angel es at an average speed of

$105 \, km/h \, (65 \, mi/h)$ and the trip takes $2h$ and $20 \, min$

On a Friday afternoon, however, heavy traffic slows you down and you drive the same distance at an average speed of only $70 km/h \, (43 mi/h)$

How much longer does it take?

\begin{align*}

d_1&=r_1t_1=

\dfrac{65\,mi}{\cancel{ h }}

\cdot 2.33\, \cancel{h}=151.45\,mi\\

t_2&=\dfrac{d_1}{r_2}=

151.45\,\cancel{mi}\cdot\dfrac{h}{43\,\cancel{mi}}=3.52\,h\\

t_\Delta&=t_2-t_1=

3.52h-2.33h

\approx 1.19\, h \approx 1\, h\, 10\, min

\end{align*}

ok I think this is correct but was not sure about the units how to use them in process

since there is 2 sets of time and rate.

also this cancel control kinda sucks should be same angle or straight and red maybe.