A bowl of water has a flat base of area A = 18.7 cm 2 and rests on a table. The

Question

A bowl of water has a flat base of area A = 18.7 cm2 and rests on a table. The height of the water is h = 10.6 cm, the weight of the water is 5.00 N, and the weight of the bowl is negligible (see figure below).

(a) Find the force exerted on the base of the bowl by the water in contact with it. (Consider the water directly above the base of the bowl.)

2. For an airplane in flight, the average speed of the air relative to the plane is 286 m/s below the wings and 314 m/s above the wings (see the figure below). The bottom of each wing has a surface area of 29.6 m2. Calculate the lift, which is the net upward force of air on the plane.

Explanation / Answer

Here ,

1)

pressure at the bottom ,

P = p*g * h + Po

P = 1.01 *10^5 + 1000 * 9.8 * .106

P = 1.0204 *10^5

force acting on the bottom = P * area

force acting on the bottom = 1.0204 *10^5 * 18.7 *10^-4

force acting on the bottom = 190.8 N

the force acting on the bottom is 190.8 N

2)

Here , v1 = 314 m/s

v2 = 286 m/s

Area , A = 29.6 m^2

Using bernoulli's theroum

P2 - P1 = 0.5 * p * (v1^2 - v2^2)

P2 - P1 =0.5 * 1.204 * (314^2 - 286^2)

P2 - P1 =10113.6 N

lift force = Area * (P2 - P1 )

lift force = 10113 * 29.6

lift force = 299400 N

the lift force is 299400 N

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