Question

Камень, брошенный вертикально вверх пролетел, двигаясь в одном направлении, 8, 8 м за первые 0, 8 с полета. 2 Найдите скорость камня на высоте 7 м. Ускорение свободного падения 10 м/с. Сопротивление воздуха пренебрежимо мало. Ответ приведите в [м/с).

Answer 1

Ответ:

Скорость камня на высоте 7 метров равна 9,2 м/с

Объяснение:

Дано:

H₁ = 8,8 м

t₁ = 0,8 с

Н₂ = 7 м

_______

V₂ - ?

1)

Запишем уравнение движения:

H₁ = V₀·t₁ - g·t₁² / 2

Разделим уравнение, разделив обе части на t₁:

H₁/t₁ = V₀ - g·t₁ / 2

V₀ = H₁/t₁ + g·t₁ / 2  = 8,8 / 0,8 + 10·0,8 / 2 =

= 11 + 4 = 15 м/с - начальная скорость камня.

2)

Найдем скорость камня на высоте Н₂.

H₂ = (V₂² - V₀²) / (-2·g)

-2·g·H₂ = V₂² - V₀²

V₂² = V₀² - 2·g·H₂

V₂ = √ (V₀² - 2·g·H₂) = √ (15² - 2·10·7) = √ 85 ≈ 9,2 м/с

Answer 2

Problem Analysis

We are given that a stone is thrown vertically upwards and travels a distance of 8.8 m in the first 0.8 s of its flight. We need to find the velocity of the stone at a height of 7 m. The acceleration due to gravity is given as 10 m/s², and air resistance can be neglected.

Solution

To solve this problem, we can use the equations of motion for uniformly accelerated motion. The equation that relates displacement, initial velocity, final velocity, acceleration, and time is:

s = ut + (1/2)at²

where: - s is the displacement - u is the initial velocity - t is the time - a is the acceleration

In this case, we know the displacement (s = 8.8 m), the time (t = 0.8 s), and the acceleration (a = 10 m/s²). We need to find the initial velocity (u) at a height of 7 m.

Let's calculate the initial velocity using the given information.

Calculation

Using the equation of motion, we can rearrange it to solve for the initial velocity (u):

u = (s - (1/2)at²) / t

Substituting the given values: - s = 8.8 m - t = 0.8 s - a = 10 m/s²

u = (8.8 - (1/2)(10)(0.8²)) / 0.8

Simplifying the equation: u = (8.8 - 4) / 0.8

u = 4.8 / 0.8

u = 6 m/s

Therefore, the initial velocity of the stone at a height of 7 m is 6 m/s.

Answer

The velocity of the stone at a height of 7 m is 6 m/s.