Question

Стрела, выпущенная из лука со скоростью 40 м/с под углом 30 градусов к горизонту, дважды побывала на высоте 15 м. Какой промежуток времени разделяет эти моменты.

Answer 1

найдем время подъема до высоты h= 15м
15=20*t -5t^2    t1=1c   t2=3c    дельта t=2 c  -  ответ
Vy=20м/с

Answer 2

Calculation of Time Interval

To calculate the time interval between the two moments when the arrow reaches a height of 15m, we can use the equations of motion for projectile motion. The time of flight for a projectile can be calculated using the formula:

Time of flight (T) = 2 * (V * sin(θ)) / g,

where: - V is the initial velocity of the projectile (40 m/s), - θ is the angle of projection (30 degrees), - g is the acceleration due to gravity (approximately 9.8 m/s^2).

Plugging in the given values, we can calculate the time of flight:

T = 2 * (40 * sin(30)) / 9.8.

Let's calculate the time interval using the given values and the formula above.

T = 2 * (40 * sin(30)) / 9.8.

Using a calculator, we find that the time of flight is approximately 4.08 seconds.

Therefore, the time interval between the two moments when the arrow reaches a height of 15m is approximately 4.08 seconds.