Question

Камень брошенный вертикально вверх с поверхности земли дважды проходит через точку на высоте 10 метров интервалом в одну секунду Найдите время от начала движения камни до момента падения на землю

Answer 1

2 сек наверно может быть но я точно не говорю что 2 сек

Answer 2

Problem Analysis

We are given that a stone is thrown vertically upwards from the surface of the Earth and passes through a point at a height of 10 meters twice, with an interval of one second between the two passes. We need to find the time it takes for the stone to fall back to the ground from the beginning of its motion.

Solution

To solve this problem, we can use the equations of motion for vertical motion under constant acceleration. The key equation we will use is:

h = ut + (1/2)gt^2

where: - h is the height of the stone above the ground, - u is the initial velocity of the stone, - g is the acceleration due to gravity (approximately 9.8 m/s^2), - t is the time elapsed.

We are given that the stone passes through a point at a height of 10 meters twice, with an interval of one second between the two passes. Let's assume the stone is thrown upwards at time t = 0.

For the first pass, when the stone reaches a height of 10 meters, we can substitute the values into the equation:

10 = u(1) - (1/2)(9.8)(1)^2 Simplifying the equation, we get:

10 = u - 4.9 For the second pass, when the stone reaches a height of 10 meters again, we can substitute the values into the equation:

10 = u(2) - (1/2)(9.8)(2)^2 Simplifying the equation, we get:

10 = 2u - 19.6 Now, we have a system of two equations with two unknowns (u and t). We can solve this system of equations to find the values of u and t.

Subtracting the first equation from the second equation, we get:

0 = u - 9.6 Simplifying the equation, we find:

u = 9.6 Substituting the value of u back into the first equation, we can solve for t:

10 = 9.6 - 4.9 Simplifying the equation, we find:

t = 0.8 Therefore, the time it takes for the stone to fall back to the ground from the beginning of its motion is 0.8 seconds.

Answer

The time from the beginning of the stone's motion to the moment it falls back to the ground is 0.8 seconds.