Question

Who exerts more pressure?
a) A girl of 50 kg wearing wheels with an area of cross section 1 cm2
b) An elephant of 4000 kg with foot area of each 250cm2

IMPORTANT POINT------2 INDICATES SQUARE

Answer 1

Well, if the girl is standing in such a way that her entire weight is being borne on her 2 heels having a combined area of 1cm² and none is being borne on the soles of her shoes, then she is exerting 50kg/cm², 25kg/cm² on each foot. Our elephant friend would be exerting its 4,000kg, weight on its four feet with a combined surface area of 250cm² which would make the pressure exerted by the elephant, 4,000kg/250cm², 16kg/cm². So, the girl is exerting more pressure than the Elephant, which is why I allow Elephants to walk on my lawn, but not girls in high heels.

Answer 2

Given:

Mass of girl = $50 kg$

Area of heels = $1cm^{2}$

Mass of elephant = $4000kg$

Area of elephant's foot $=250cm^{2}$

To find:

Among the girl's heels and elephant foot, who exerted more pressure.

Explanation:

• Pressure is defined as the force exerted by any object over any body with respect to its area.

          Mathematically, $Pressure(P)=\frac{Force (F)}{Area (A)}$

• Hence, if area of the object is less, then the pressure exerted over the body is more and if the area is more, pressure exerted will be less.

• For example, while bursting a balloon, a safety pin may be used as compared to using hand. This is because safety pin has a very pointed end and thus, exerts more pressure to burst a balloon. Whereas while using our hand, which has a larger surface area and hence we have to apply more force.

Solution:

Step 1

We have,

Mass of girl  $(m)=50 kg$

Area of cross section of heels $(A)=1cm^{2}=10^{-4}m^{2}$

Hence,

Force exerted by girl = her weight = $mg$ =$5000N$

Therefore,

Pressure exerted will be $=\frac{5000}{10^{-4} }$

                                        = $5$ × $10^{7}N/m^{2}$

Hence, pressure exerted by heels of girls will be $5$ × $10^{7}Pa$.

Step 2

Mass of elephant = $4000 kg$

Area of elephants foot $(A)=250cm^{2}$

                                            $=250$ × $10^{-4}m^{2}$

Force exerted by elephant $=mg$  $=4$ × $10^{4} kg$

Hence,

Pressure exerted by foot of elephant = $\frac{4*10^{4} }{250*10^{-4} }$

                                                         $=$ $0.016$ × $10^{8}N/m^{2}$

Hence, pressure exerted by elephants foot is $1.6$ × $10^{6} Pa$.

Final answer:

Hence, we can see that the girls heels exert more pressure as compared to the elephant.