Suzie (of mass 98 kg) is roller-blading down
the sidewalk going 40 miles per hour. She
notices a group of workers down the walkway
who have unexpectedly blocked her path, and
she makes a quick stop in 1.1 seconds.
What is Suzie's average acceleration?
Answer in units of m/s^2. Also, what force was exerted to stop her, and where did this force come from?
Okay, so for the first part I subtracted 40 from 0 (for initial and final velocity) and got -40. Then I divided by 2 to get 20. I divided it all by 1.1 and got an answer, but that answer is in mph/s. How do I convert it? Is that how I'm supposed to do it?
Then for the force I multiplied 98 by my answer for acceleration. I got an answer, but I know it's wrong because I didn't convert the last answer.
As far as the force that is stoping her, isn't it a combination of the friction of rollerskates, gravity, the friction of her against air, and the ground pushing up?
2007-02-16
00:27:27
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4 answers
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asked by
Nikita R
2
in
Physics