Question

(a) A boy weighs 50 N. The area of contact of his two feet is 10 cm? What pressure does he exert on the ground if he stands on one foot?

(b) A man weighs 250 N. Suppose he stands on a pointed edge with base area 5 cm?. How much pressure does he exert on the ground?

(c) Now compare (i) and (ii) to find out the following.

(i) Who exerts more force on the ground, the boy in (i) or the man in (ii)?

(ii) Who exerts greater pressure on the ground, the boy or the man?

(iii) Who is likely to sink into the ground, the man standing on a pointed edge or the boy
standing on one foot and why?​

Answer 1

Answer:

(a) When he stands on one foot, the effective area becomes half i.e., 5 cm².

Hence,

$Pressure = \frac{Force}{Area}=\frac{50}{5*10^{-4}} Pascal=10^5\,Pascal$

(b) $Pressure=\frac{250}{5*10^{-4}}=5*10^{5}\,Pascal$

(c) (i) More force will be exerted by the man in (b), because he has more weight.

(c) (ii) The man in (b) is exerting more pressure.

(c) (iii) Since the man in (b) is exerting more pressure, the man is more likely to sink into the ground.

Answer 2

Answer:

(a) When he stands on one foot, the effective area becomes half i.e., 5 cm².

Hence,

Pressure = \frac{Force}{Area}=\frac{50}{5*10^{-4}} Pascal=10^5\,PascalPressure=AreaForce=5∗10−450Pascal=105Pascal

(b) Pressure=\frac{250}{5*10^{-4}}=5*10^{5}\,PascalPressure=5∗10−4250=5∗105Pascal

(c) (i) More force will be exerted by the man in (b), because he has more weight.

(c) (ii) The man in (b) is exerting more pressure.

(c) (iii) Since the man in (b) is exerting more pressure, the man is more likely to sink into the ground.

Explanation:

Pressure = Force / Area