Why a sidewalk has cracks every few feets

2 answers:

7 0

Because sidewalks are usually in places where the sun can shine
on them most of the day. Even if the sun can't shine directly on them,
the weather can get hot. Either way, the material that the sidewalk is
made of can often get hot. You know that when things heat up they
"expand" ... they actually get slightly bigger. If there were no spaces
in the sidewalk for it to get bigger, then when the material got hot and
tried to get bigger, it would crack and break, and the whole sidewalk
would be all broken up in a few months.

gladu [14]4 years ago

4 0

It is because if it was one big piece, the concrete would buckle and break just like bridges.

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Missing part in the text: "...the charges are <span>separated by a distance of 30.0 cm."
</span>
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The point midway between the two charges is located 15.0 cm from one charge and 15.0 from the other charge. The electric field generated by each of the charges is
$E=k_e \frac{q}{r^2}$
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Q is the value of the charge
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While the electric field generated by the second charge is
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Both charges are positive, this means that both electric fields are directed toward the charge. Therefore, at the point midway between the two charges the two electric fields have opposite direction, so the total electric field at that point is given by the difference between the two fields:
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