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3 years ago

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Brad is working on a speed problem in physics class. The problem tells him that a girl runs from her house to the park 0.05 km a

way in 10 s. Brad calculates that her speed is 0.005 m/s. Is he correct? If not, explain the flaw or flaws in his problem solving process.

2 answers:

Dmitriy789 [7]3 years ago

7 0

It is corecct becasue it 10 s more added from 0.05

Olegator [25]3 years ago

3 0

Answer:

He is incorrect! Her speed was 5m/s.

Explanation:

For calculating the speed, first we shall remember that:

$v=\dfrac{d}{t}$

Where $v$ is the speed, $d$ is the distance travelled and, $t$ is the time it takes to travel distance $d$ .

So one migth think that velocity can be easely compute:

$v=\dfrac{0.05}{10}$

$v=0.005\dfrac{m}{s}$

Be carefull, he does not make a proper dimensional analisis!

Before computing the speed we must know in what dimensions our values are.

$d=0.05km$ , distances is measure in Kilometers.

$t=10s$ , time is measure in seconds.

If we want our speed to be in $m/s$ , first we need to be sure that our values are expressed in meters and seconds.

Time is already expressed in seconds, distance is not in Kilometers.

So

$0.05Km=50m$ ,

now we can compute the speed:

$v=\dfrac{d}{t}$

$v=\dfrac{50m}{10s}$

$v=\5dfrac{m}{s}$

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