Question

Шарик массой 200 г падает с высоты 20м с начальной скоростью, равной нулю. Его кинетическая энергия в момент перед ударом о землю равна 35 Дж. Какова потеря механической энергии шарика за счет сопротивления воздуха?

Answer 1

Найдем сначала Екин без сопротивления воздуха:
Екин=mV^2/2   нам не известна его скорость, значит найдем её по формуле нахождения ускорения, где ускорение будет g-ускорение свободного падения.

g = V-Vнулевое/t     где Vнулевое=0 из условия.Значит  V=gt     

нам не известно время, найдем его по этой формуле:   

h = gt^2/2      выразим время.  t=√2h/g =√2*20/10=√4=2c

V=10*2=20 м/c

Ну и найдем саму Екин без сопротивления воздуха 

Екин=0.2*20^2/2=40Дж 

А теперь найдем потери   40-35=5Дж

Надеюсь помог))

Answer 2

Calculation of Mechanical Energy Loss due to Air Resistance

To calculate the mechanical energy loss of the ball due to air resistance, we need to consider the initial kinetic energy of the ball, the potential energy at the starting height, and the final kinetic energy just before impact.

Given: - Mass of the ball (m) = 200 g = 0.2 kg - Height (h) = 20 m - Initial velocity (v0) = 0 m/s - Kinetic energy just before impact (KE) = 35 J

The mechanical energy of the ball is the sum of its potential energy and kinetic energy: Mechanical Energy (ME) = Potential Energy (PE) + Kinetic Energy (KE)

The potential energy at the starting height is given by: PE = m * g * h where g is the acceleration due to gravity (approximately 9.8 m/s^2).

Let's calculate the potential energy: PE = 0.2 kg * 9.8 m/s^2 * 20 m = 39.2 J.

Now, we can calculate the initial kinetic energy (KE_initial) using the formula: KE_initial = 0.5 * m * v0^2 Since the initial velocity is zero, the initial kinetic energy is also zero.

The mechanical energy at the start is the sum of the potential energy and initial kinetic energy: ME_start = PE + KE_initial = 39.2 J + 0 J = 39.2 J.

The mechanical energy just before impact is given as 35 J (KE).

The mechanical energy loss due to air resistance is the difference between the mechanical energy at the start and just before impact: Mechanical Energy Loss = ME_start - KE = 39.2 J - 35 J = 4.2 J.

Therefore, the mechanical energy loss of the ball due to air resistance is 4.2 J.

Please note that this calculation assumes that the only form of energy loss is due to air resistance. Other factors, such as friction with the surface, are not considered in this calculation.

Let me know if there's anything else I can help you with!