Question

Тело массой 500г брошено под углом к горизонту со скоростью 18м/с с высоты 10м и упало со скоростью 22м/с. Чему равна работа по преодалению сил сопротивления??

Answer 1

Дано: m=500г=0.5кг   v0=18 м/с    v=22м/с   h=10 м  Найти:А-?

Решение:полная механическая энергия в время броска равна E1=П+К=mgh+mv0^2/2

полная механич энергия во время падения равна Е2=К+А = mv^2/2+А ( т.к. потенциальная энергия равна 0)

по закону сохранения энергии Е1=Е2

 mgh+mv0^2/2 =  mv^2/2+А

А=m(gh+v0^2/2-v^2/2)=0.5(10*10+18^2/2-22^2/2)= 10 Дж

Answer 2

Calculation of Work Done Against Resistance

To calculate the work done against resistance, we need to consider the initial and final kinetic energies of the object. The work done against resistance is equal to the change in kinetic energy.

Given: - Mass of the object (m) = 500 g = 0.5 kg - Initial velocity (u) = 18 m/s - Final velocity (v) = 22 m/s - Height (h) = 10 m

First, let's calculate the initial and final potential energies of the object using the formula:

Potential Energy (PE) = mgh

Where: - m is the mass of the object - g is the acceleration due to gravity (approximately 9.8 m/s^2) - h is the height

Initial potential energy (PEi) = m * g * h Final potential energy (PEf) = m * g * 0

Since the object falls to the ground, the final potential energy is zero.

Next, let's calculate the initial and final kinetic energies of the object using the formula:

Kinetic Energy (KE) = (1/2) * m * v^2

Where: - m is the mass of the object - v is the velocity

Initial kinetic energy (KEi) = (1/2) * m * u^2 Final kinetic energy (KEf) = (1/2) * m * v^2

The work done against resistance is equal to the change in kinetic energy:

Work Done Against Resistance = KEf - KEi

Let's calculate the values:

Initial potential energy (PEi) = 0.5 kg * 9.8 m/s^2 * 10 m = 49 J

Initial kinetic energy (KEi) = (1/2) * 0.5 kg * (18 m/s)^2 = 162 J

Final kinetic energy (KEf) = (1/2) * 0.5 kg * (22 m/s)^2 = 242 J

Work Done Against Resistance = KEf - KEi = 242 J - 162 J = 80 J

Therefore, the work done against resistance is 80 Joules.