How much kinetic energy is released

In summary, an object initially at rest in free space explodes into three equal mass segments, with two segments moving at equal speeds of 20 m/s at a 60° angle. The amount of kinetic energy released in this explosion is 2.0 kJ.
  • #1
gijungkim
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Homework Statement


A 6.0-kg object, initially at rest in free space, “explodes” into three segments of equal mass. Two of these segments are observed to be moving with equal speeds of 20 m/s with an angle of 60° between their directions of motion. How much kinetic energy is released in this explosion?

a.2.4 kJ

b.2.9 kJ

c.2.0 kJ

d.3.4 kJ

e.1.2 kJ

Homework Equations


m1v1 + m2v2 + m3v3 = m1v1f + m2v2f + m3v3f
K = 0.5*m*v^2

The Attempt at a Solution


The answer is c, 2000J, but I got 1500J and I don't know where I did wrong. Can anyone help me?
My work is in the picture
 

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  • #2
Nevermind I got it. Just made an algebric mistake..
 

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  • #3
Even so, herer's a tip: place the x-axis halfway between m1 and m2. That way py cancels. Less chance of error. But you do need cos(60) which at first you had 0 :smile: !
 
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  • #4
BvU said:
Even so, herer's a tip: place the x-axis halfway between m1 and m2. That way py cancels. Less chance of error. But you do need cos(60) which at first you had 0 :smile: !
Thanks for the tip!
 

Related to How much kinetic energy is released

1. What is kinetic energy?

Kinetic energy is the energy that an object possesses due to its motion.

2. How is kinetic energy calculated?

Kinetic energy (KE) is calculated by multiplying the mass (m) of an object by the square of its velocity (v) and dividing by 2, represented by the equation KE = 1/2 * m * v^2.

3. What factors affect the amount of kinetic energy released?

The amount of kinetic energy released depends on the mass and velocity of an object. The greater the mass and velocity, the more kinetic energy will be released.

4. What are some common units for measuring kinetic energy?

Kinetic energy is typically measured in joules (J) in the metric system and foot-pounds (ft-lb) in the imperial system.

5. Can kinetic energy be converted into other forms of energy?

Yes, kinetic energy can be converted into other forms of energy, such as potential energy, thermal energy, and electrical energy.

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