An elephant weighing 40,000 N stands on one foot of area 000 cm2 whereas a girl weighing 400 N is standing on one ‘stiletto’ heel of area 1 cm2. (Pictures)
(a) Which of the two, elephant or girl, exerts a larger force on the ground and by how much?
(b) What pressure is exerted on the ground by the elephant standing on one foot?
(c) What pressure is exerted on the ground by the girl standing on one heel?
(d) Which of the two exerts larger pressure on the ground: elephant or girl?
(e) What is the ratio of pressure exerted by the girl to the pressure exerted by the elephant?
Weight of the elephant = 40000N
Area of 1 foot = 1000cm2 = 0.1m2
Weight of girl = 400N
Area of heel = 1cm2 = 1 × 10-⁴ m2
(a) Since, elephant has a larger weight therefore it exerts a larger force on the ground by 40000N - 400N = 39600N
(b) We know,
Pressure = Force/ Area
= 40000/ 0.1
= 400000N/m2
(c) We know,
Pressure= Force/ Area
= 400/ 10-⁴
=4000000N/m2
(d) The girl exerts a larger pressure on the ground.
(e) Ratio = (Pressure exerted by the girl)/ (Pressure exerted by the elephant)
= 4000000/ 400000
= 10/1
Hence, the pressure exerted by the girl is 10 times the pressure exerted by the elephant.