Question

Si un proyectil asciende verticalmente, y después de 3 segundos alcanza su altura máxima, calcule la velocidad que lleva a la mitad de su trayectoria descendente

Answer 1

The speed is 20.8 m/s

Explanation:

If a projectile ascends vertically, and after 3 seconds it reaches its maximum height, calculate the velocity that it carries to the middle of its downward trajectory

Let the maximum height is h and initial velocity is u.

From first equation of motion

v = u + at

0 = u - g x 3

u = 3 g.....(1)

Use third equation of motion

`v^2 = u^2 - 2 gh \\\\0 = 9 g^2 - 2 gh \\\\h = 4.5 g`

Let the speed at half the height is v'.

`v^2 = u^2 + 2 gh \\\\v'^2 = 0 + 2 g* 2.25 g\\\\v'^2 = 4.5* 9.8*9.8\\\\v' = 20.8 m/s`