Question

Тело брошено вертикально вверх со скоростью15м/с. С Какой скоростью оно упадет обратно на землю? Трением о воздух пренебречь

Answer 1

Ответ:

По закону сохранения энергии -  скорость в момент падения равна скорости в момент взлета.  

Ответ: 15 м/c

Объяснение:

Answer 2

Calculation of the Time Taken to Reach Maximum Height

To determine the speed at which the object will fall back to the ground, we first need to calculate the time it takes for the object to reach its maximum height.

The initial velocity of the object is given as 15 m/s, and we can assume that the acceleration due to gravity is approximately 9.8 m/s^2.

Using the equation of motion for vertical motion, we can calculate the time taken to reach the maximum height. The equation is:

v = u + at

Where: - v is the final velocity (0 m/s at maximum height) - u is the initial velocity (15 m/s) - a is the acceleration due to gravity (-9.8 m/s^2) - t is the time taken to reach the maximum height

Rearranging the equation to solve for t, we have:

t = (v - u) / a

Substituting the values, we get:

t = (0 - 15) / -9.8

Calculating this, we find that the time taken to reach the maximum height is approximately 1.53 seconds.

Calculation of the Total Time of Flight

Since the object takes 1.53 seconds to reach the maximum height, the total time of flight can be calculated by doubling this value. This is because the time taken to reach the maximum height is equal to the time taken to fall back to the ground.

Therefore, the total time of flight is approximately 3.06 seconds.

Calculation of the Final Velocity

To calculate the final velocity at which the object will fall back to the ground, we can use the equation of motion:

v = u + at

Where: - v is the final velocity - u is the initial velocity (0 m/s at maximum height) - a is the acceleration due to gravity (-9.8 m/s^2) - t is the time taken to reach the maximum height (1.53 seconds)

Substituting the values, we have:

v = 0 + (-9.8) * 1.53

Calculating this, we find that the final velocity at which the object will fall back to the ground is approximately -15 m/s. The negative sign indicates that the velocity is directed downwards.

Conclusion

Therefore, the object will fall back to the ground with a speed of approximately 15 m/s.