Question

A physics book has a height of 25.8 cm, a width of 20.2 cm, and a thickness of 2.90 cm.
(a) What is the density of the physics book if it weighs 20 N? kg/m³
(b) Find the pressure that the physics book exerts on a desktop when the book lies face up. Pa
(c) Find the pressure that the physics book exerts on the surface of a desktop when the book is balanced on its spine. Pa

Answer 1

Answer:

(a) 1350.44 kg/m^3

(b) 383.8 Pa

(c) 3414.45 Pa

Explanation:

height, h = 25.8 cm

width, w = 20.2 cm

thickness, t = 2.90 cm

(a) weight = 20 N

Weight = mass x gravity

20 = m x 9.8

m = 2.041 kg

Volume of book = height x width x thickness

V = 25.8 x 20.2 x 2.90

V = 1511.364 cm^3 = 1.511 x 10^-3 m^3

Mass = volume x density

2.041 = 1.511 x 10^-3 x d

d = 1350.44 kg/m^3

(b) Pressure

P = thickness x density x g

P = 2.90 x 10^-2 x 1350.44 x 9.8

P = 383.8 Pa

(c) Pressure

P = height x density x g

P = 0.258 x 1350.44 x 9.8

P = 3414.45 Pa