# Projectile and conservation of motion

1. Oct 31, 2005

### hoseA

A projectile of mass 6 kg is fired with an
initial speed of 74 m/s at an angle of 20 degrees with
the horizontal. At the top of its trajectory,
the projectile explodes into two fragments of
masses 3.7 kg and 2.3 kg . The 2.3 kg fragment
lands on the ground directly below the point
of explosion 4.4 s after the explosion.
The acceleration of gravity is 9.81 m/s^2 .

A) Find the magnitude of the velocity of the
3.7 kg fragment immediatedly after the explo-
sion. Answer in units of m/s.

B) Find the distance between the point of firing
and the point at which the 3.7 kg fragment
strikes the ground. Answer in units of km.

C) How much energy was released in the explo-
sion? Answer in units of kJ.

Any help appreciated.

2. Oct 31, 2005

### whozum

Interesting problem but you need to show some effort.

3. Oct 31, 2005

### hoseA

I tried to find the velocity:

MVix = MVfx

(6)(cos(20))(125) = (3.7)(0) + (3.7)(Vf2x)
So get Vf2 is 181.40153 m/s.

But this is not the answer. I guess this is only the x component of it. How to get the y and put it together?

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