Question

Помогите, пожалуйста, с физикой. Тело бросают вертикально вниз с поверхности земли со скоростью 15 м/с в яму. Через какое время тело упадет на дно ямы? Глубина ямы 20 метров. Можно решение

Answer 1

H=(V^2-V0^2)/(2g),
V=0, так как тело бросают
h=V0^2/2g=225/20=11,25м
h=gt^2/2=5t^2,
 t^2=11,25/5=2,25
 t=1,5c
Ответ:  t=1,5c

Answer 2

Вот, надеюсь понятно. Удачи!
h=(V^2-V0^2)/-2g, V=0, g с минусом, потому что направлено против векторов V0,h.h=V0^2/2g=225/20=11,25м; h=gt^2/2=5t^2, t^2=11,25/5=2,25, t=1,5c

Answer 3

Problem Analysis

We are given that an object is thrown vertically downwards with an initial velocity of 15 m/s into a hole with a depth of 20 meters. We need to find the time it takes for the object to reach the bottom of the hole.

Solution

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

s = ut + (1/2)at^2

Where: - s is the displacement (depth of the hole) = -20 m (negative because the object is moving downwards) - u is the initial velocity = 15 m/s - t is the time we want to find - a is the acceleration due to gravity = -9.8 m/s^2 (negative because it acts in the opposite direction to the object's motion)

Substituting the given values into the equation, we can solve for t:

-20 = 15t + (1/2)(-9.8)t^2

Simplifying the equation, we get a quadratic equation:

-4.9t^2 + 15t + 20 = 0

We can solve this quadratic equation using the quadratic formula:

t = (-b ± √(b^2 - 4ac)) / (2a)

Where: - a = -4.9 - b = 15 - c = 20

Let's calculate the value of t using the quadratic formula.

Calculation

Using the quadratic formula, we have:

t = (-15 ± √(15^2 - 4(-4.9)(20))) / (2(-4.9))

Simplifying further:

t = (-15 ± √(225 + 392)) / (-9.8)

t = (-15 ± √617) / (-9.8)

Calculating the square root of 617, we get:

t ≈ (-15 ± 24.8) / (-9.8)

Now, we have two possible values for t:

t1 ≈ (-15 + 24.8) / (-9.8) ≈ 1.07 seconds

t2 ≈ (-15 - 24.8) / (-9.8) ≈ 3.06 seconds

Since time cannot be negative, we discard the negative value. Therefore, the time it takes for the object to reach the bottom of the hole is approximately 1.07 seconds.

Answer

The object will fall to the bottom of the hole in approximately 1.07 seconds.