Question

Книга массой 1 кг упала со стола высотой 1 м. В момент падения ско- рость книги равнялась примерно 4,2 м/с. Найдите величину работы сил сопро- тивления воздуха за время всего полёта. Сравнить её с величиной работы силы тяжести в процессе такого движения книги.

Answer 1

Работа силы тяжести A=m*g*h=1*9,8*1=9,8 Дж
Работа силы сопротивления Ac=A-m*V^2/2=9,8-(1*4,2^2/2)=1 Дж
A/Ac=9,8/1=9,8
A>Ac в 9,8 раза.

Answer 2

Calculation of Work Done by Air Resistance

To calculate the work done by air resistance during the entire flight of the book, we need to know the distance traveled by the book. Since the book fell from a height of 1 meter, we can assume that the distance traveled is also 1 meter.

The work done by air resistance can be calculated using the formula:

Work = Force × Distance

The force of air resistance can be calculated using the formula:

Force = 0.5 × ρ × A × C × v^2

Where: - ρ is the density of air - A is the cross-sectional area of the book - C is the drag coefficient of the book - v is the velocity of the book

Unfortunately, the given information does not provide the values of ρ, A, and C. Therefore, we cannot calculate the exact work done by air resistance.