Question

7. A girl weighing 50 kg is standing on pencil heels. Each having an area of cross- section 1cm². An elephant weighing 200 kg and foot area with a cross-section of 250 cm is standing on the floor. Which of the two exerts more pressure on the floor? (Given acceleration due to gravity = 10 m/s?)​

Answer 1

Answer:

We know

Pressure=Force/Area

we don't have Force,so for finding force, we've to use it's formula

that is

Force= Mass × Acceleration

Let's take the girl's case first

Force= 50×a

standing on the floor means,there is acceleration due to gravity,and acceleration due to gravity makes,a=g

and the value of g = 10m/s²(given)

Force=50×10

Force=500 N

Now finding the pressure exerted by her

Before, checking area,

We've a term Cross Section here

that is Cross Section of each feet.

Each has a cross section of 1 cm to the power of 2,and we know a girl can stand only 2 feets,so making it 2 cm to the power of 2,so we've to convert it into m

as the result is 0.0002m²

so, that's what her area is

Now Find pressure

Pressure=Force/Area

Pressure=500/0.0002

Pressure= 2,500,000 pa

Now finding the elephant's case

Force=200×a

standing on the floor means,there is acceleration due to gravity,and acceleration due to gravity makes,a=g

and the value of g = 10m/s²(given)

Force=200×10

Force=2000 N

Each has a cross section of 250 cm to the power of 2×4,and we know an elephant can stand 4 feets,so making it 1000 cm to the power of 2,so we've to convert it into m

that is

1000 cm²= 0.1m²

Now finding pressure

Pressure=Force×Acceleration

Pressure=2000/0.1

Pressure=20000 pa

therefore the girl exerts more pressure than the elephant.