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July 9th, 2017, 07:17 PM   #1
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Help with a KA problem (Slope,speed, rate)




--------

If the speed is constant why cant I divide the time by the distance
of any of the entries instead of using the slope?
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July 9th, 2017, 08:09 PM   #2
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Because she did not start right away. She rode at a constant speed once she finished getting ready, but that means that her average speed was not constant from the time she got the call. It was only constant once she started pedaling.

She could travel 5 km in 40 minutes after the call, giving an average rate of 0.125 km / min from the time of the call.

She could travel 7 km in 52 minutes after the call, giving an average rate of about 0.135 km /min from the time of the call.

So let's set it up as a system of equations.

$\text {c = time spent cycling}.$

$\text {g = time spent getting ready}.$

$\text {t = total time}.$

$\text {r = constant speed while cycling}.$

$\text {d = distance traveled}.$

$\therefore d = 0 * g + c * r = cr$ because no distance is traveled during g.

$\text {And } t = c + g \implies g = (t - c) \implies d = cr = (t - g)r = tr - gr.$

$7 = 52r - gr.$

$5 = 40r - gr.$

$\therefore 7 - 5 = (52r - gr) - (40r - gr) \implies 2 = 12r.$

What does that mean? It means she pedals 2 kilometers in 12 minutes.

So how long does it take her to pedal 1 kilometer?
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July 9th, 2017, 11:17 PM   #3
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Triple dots = therefore and arrows means implies? right?


I quoted your post to see but still getting the symbols down.
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July 10th, 2017, 12:03 AM   #4
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Quote:
Originally Posted by Rujaxso View Post
Triple dots = therefore and arrows means implies? right?
That is usually the case yes.

You should be able to quote this post and see,

$\therefore$,

$\implies$.
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