Question

Тело бросили вертикально вверх с высоты 30 м с начальной скоростью 20м/с. через какое время оно упадет на землю

Answer 1

По формуле
30м: 20м/с= 1.5 с

Answer 2

Calculation of the Time it Takes for the Object to Fall

To calculate the time it takes for the object to fall to the ground, we can use the equations of motion. The object is thrown vertically upwards from a height of 30 m with an initial velocity of 20 m/s.

The equation we can use to calculate the time is:

h = V0 * t + (1/2) * g * t^2

Where: - h is the height (30 m) - V0 is the initial velocity (20 m/s) - t is the time - g is the acceleration due to gravity (approximately 9.8 m/s^2)

To solve for t, we rearrange the equation:

(1/2) * g * t^2 + V0 * t - h = 0

Now we can substitute the values into the equation and solve for t.

Using the quadratic formula:

t = (-V0 ± sqrt(V0^2 - 4 * (1/2) * g * (-h))) / (2 * (1/2) * g)

Simplifying the equation:

t = (-V0 ± sqrt(V0^2 + 2 * g * h)) / g

Now we can substitute the values into the equation and solve for t.

Using the given values: - V0 = 20 m/s - h = 30 m - g = 9.8 m/s^2

Substituting the values into the equation:

t = (-20 ± sqrt(20^2 + 2 * 9.8 * 30)) / 9.8

Calculating the value inside the square root:

sqrt(20^2 + 2 * 9.8 * 30) ≈ sqrt(400 + 588) ≈ sqrt(988) ≈ 31.43

Substituting the value into the equation:

t = (-20 ± 31.43) / 9.8

Calculating the two possible values for t:

t1 = (-20 + 31.43) / 9.8 ≈ 1.14 seconds

t2 = (-20 - 31.43) / 9.8 ≈ -5.15 seconds

Since time cannot be negative in this context, we discard the negative value.

Therefore, the object will take approximately 1.14 seconds to fall to the ground.