Physics, asked by aryanraj5129, 1 year ago



13. A girl of weight 400 N holding a bag of weight 40 N
on her head. If she is standing on semicircular heels
of periphery 72/7cm,
, then net pressure exerted on
the floor by the girl is

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Answers

Answered by abhi178
13

weight of girl = 400 N

weight of bag held by girl = 40 N

so, net weight applied on heel = 400N + 40N = 440 N

periphery of semicircular heels = 72/7

⇒ perimeter of semicircle = 72/7

⇒πr + 2r = 72/7

⇒r(22/7 + 2) = 72/7

⇒r(36)/7 = 72/7

⇒r = 2cm

so, area of semicircular heel , A = πr²

= 22/7 (2 × 10^-2)² m²

= 88/7 × 10^-4 m²

now, pressure = Net force/area

= 440/(88/7 × 10^-4)

= 70/2 × 10⁴ N/m²

= 3.5 × 10^5 N/m²

hence, option (3) is correct choice.

Answered by rehmanJ7
10

Answer:

Option (3) is the right answer

Explanation:

weight of the  girl = 400 N

weight of  the bag  = 40 N

Total  weight applied by the girl= 400N + 40N = 440 N

perimeter of semicircle = 72/7

Perimeter=Circumference+Diameter

In this case Circumference will be half because circle is semi so

For complete circle Circumference=π*d=π*2*r=2πr

For semi circle Circumference=2πr/2=πr

and Diameter will remains 2*r

so,

πr + 2*r = 72/7

r(22/7 + 2) = 72/7

r(36)/7 = 72/7=72/36=2 cm

r = 2 cm

so, area of semicircle = A = πr²

= 3.1416 *(2 × 10^-2)² m²

= 12.56* 10^-4 m²

we know that

pressure = force/area= 440/(12.56× 10^-4)

= 3.5 × 10^5 N/m²

Option (3) is correct answer

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