Calculating Total Kinetic Energy After Explosion

[Grogerian]

Homework Statement

Find the total kinetic energy in the system. a explosion fires two pieces both 7.3m high and 11.2m horizontally total kinetic energy done by the explosion the first piece is 15kg, the second 26kg?

Homework Equations

kinematics
Ke=1/2(mv²)

The Attempt at a Solution

I found that Vi(y) = \sqrt{2(9.81)(-7.3)} = 11.96 m/s do i just use this to find the total energy done? or do i need to consider the x-dir as well, If so how do i do that?

 

[tiny-tim]

Homework Statement

Find the total kinetic energy in the system. a explosion fires two pieces both 7.3m high and 11.2m horizontally total kinetic energy done by the explosion the first piece is 15kg, the second 26kg?
…
I found that Vi(y) = \sqrt{2(9.81)(-7.3)} = 11.96 m/s do i just use this to find the total energy done? or do i need to consider the x-dir as well, If so how do i do that?

Hi Grogerian!

The KE depends on the total speed, as you know, so V_y is obviously not enough unless V_x is zero.

(but I can't help any furher, as I don't understand the question. )

 

[LowlyPion]

Homework Statement

Find the total kinetic energy in the system. a explosion fires two pieces both 7.3m high and 11.2m horizontally total kinetic energy done by the explosion the first piece is 15kg, the second 26kg?

Homework Equations

kinematics
Ke=1/2(mv²)

The Attempt at a Solution

I found that Vi(y) = \sqrt{2(9.81)(-7.3)} = 11.96 m/s do i just use this to find the total energy done? or do i need to consider the x-dir as well, If so how do i do that?

Velocity is the sum of the components, so yes, you do need to determine the x component.

Since you can figure the time to drop 7.3m from the peak and you know that will be half the time of its flight, and you know that is 7.3m = 1/2 g*t². Now you can figure how fast it was to go 11.3m.