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alissa3329
14.04.2020 •
Physics
An object initially at rest explodes in two fragments of masses 5 kg and 7.5 kg that move in diametrically opposite directions. If the speed of the first fragment is 8.1 m/s, find the internal energy of the explosion.
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Ответ:
Explanation:
Given that,
The object is initially at rest. I.e Initial velocities u = 0m/s
The object explodes into two fragment
Let the first fragment mass be Ma = 5kg
Let the second fragment mass be Mb = 7.5kg
The objects move in opposite direction
The speed or the first fragment is Va = 8.1m/s
Internal energy of the explosion.
From the conservation of momentum
Momentum before collision = momentum after collision
Momentum P = mv
Momentum is a vector quantity, so since the fragment moves in opposite direction, let assume that Ma moves in positive direction and Mb moves in negative direction
Then,
(Ma+Mb)•u = Ma•-Va + Mb•Vb
0 = —5 × 8.1 + 7.5Vb
0 = —40.5 + 7.5Vb
7.5Vb = 40.5
Vb = 40.5/7.5
Vb = 5.4m/s
Now using conservation of energy
Total kinetic energy of the fragment is equal to energy of explosion
K.E = ½Ma•Va² + ½Mb•Vb²
K.E = ½ × 5 × 8.1² + ½ × 7.5 × 5.4²
K.E = 164.025 + 109.35
K.E = 273.375 J
Ответ:
60 Watts
Explanation:
60w Mean 60 watts hope this helps :)