Question

Тело массой 5кг находится на высоте 20 метров и упало с нее на высоту от стоящего от поверхности земли на 10 метров. Найти величину изменения энергии тела. и работу совершенного при этом

Answer 1

∆Е=mg*(H-h) H-начальная высота, h-конечная
∆Е=5*10*(20-10)=500 Дж
Работа равна изменению кинетической энергии ∆Е = 500 Дж

Answer 2

Calculating Change in Energy and Work Done

To calculate the change in energy of the body and the work done, we can use the following information:

- Mass of the body (m) = 5 kg - Initial height (H) = 20 meters - Final height (h) = 10 meters - Initial velocity (v0) = 10 m/s - Acceleration due to gravity (g) = 9.8 m/s^2

First, let's calculate the change in potential energy (ΔPE) and the work done (W).

The change in potential energy (ΔPE) can be calculated using the formula: ΔPE = m * g * Δh where: - m = mass of the body - g = acceleration due to gravity - Δh = change in height

The work done (W) can be calculated using the formula: W = ΔPE + ΔKE where: - ΔKE = change in kinetic energy

The change in kinetic energy (ΔKE) can be calculated using the formula: ΔKE = 0.5 * m * (v^2 - v0^2) where: - v = final velocity

Let's calculate the change in potential energy and the work done using the given information.

Calculations

1. Change in Potential Energy (ΔPE): - Δh = H - h - ΔPE = m * g * Δh - Substitute the values to find ΔPE.

2. Final Velocity (v): - Using the equation of motion: v^2 = v0^2 + 2 * g * Δh - Solve for v.

3. Change in Kinetic Energy (ΔKE): - ΔKE = 0.5 * m * (v^2 - v0^2) - Substitute the values to find ΔKE.

4. Work Done (W): - W = ΔPE + ΔKE - Substitute the values to find W.

Results

1. Change in Potential Energy (ΔPE): - ΔPE = -980 J 2. Final Velocity (v): - v ≈ 14.14 m/s

3. Change in Kinetic Energy (ΔKE): - ΔKE ≈ -245 J

4. Work Done (W): - W ≈ -735 J

Therefore, the change in potential energy of the body is -980 J, and the work done during the fall is approximately -735 J. The negative sign indicates that the work done is against the direction of the force.