Question

Question 51:
A girl is wearing a pair of flat shoes. She weighs 550 N. The area of contact of one shoe with the ground is 160 cm2. What pressure will be exerted by the girl on the ground :
(a) if she stands on two feet ?
(b) if she stands on one foot ?

Lakhmir Singh Physics Class 9

Answer 1

Answer:

a) 1718.75 N/m^2

b) 3437.5 N/m^2

Explanation:

The girl's weight in the above given problem is 550N. As we know that weight is the force with which earth attracts every body towards itself.

So, F=550N.

Now, the contact of one of her feet with the ground has the area of 160cm^2.

Converting 160cm^2 to m^2 , we get 0.16m^2.

To find the pressure we apply the formula of:

Pressure = Force applied/ Area

a) So, if the girl is standing on two of her feet, then the area covered will be double. Therefore 0.16×2 = 0.32 m^2.

So, Pressure= 550/0.32

= 1718.75 N/m^2

b) Now, when the girl stands on one of her feet, the area covered is 0.16m^2.

So, Pressure = 550/ 0.16

= 3437.5 N/m^2