From the edge of a cliff, a 0.55 kg projectile is launched with an initial kinetic energy of 1550 J. The projectile's maximum upward displacement from the launch point is +140 m. What are the (a) horizontal and (b) vertical components of its launch velocity?

(a) 38.5m/s

(b) 64.4m/s

Explanation:

First, we can obtain the launch speed from the definition of kinetic energy:

Plugging in the given values, we obtain:

Now, from the conservation of mechanical energy, considering the instant of launch and the instant of maximum height, we get:

And with the known values, we compute:

Finally, to know the components of the launch velocity, we use trigonometry:

It means that the horizontal component of the launch velocity is 38.5m/s (a) and the vertical component is 64.4m/s (b).