A mass of 20 kg moving with a speed of 10 m/s collides with another stationary mass of 5 kg. As a result of the collision, the two masses stick together. The kinetic energy of the composite mass will be:
Correct answer: B. 800 J
- A. 600 J
- B. 800 J
- C. 1000 J
- D. 1200 J
Explanation
To find the kinetic energy of the combined masses after the collision, first apply the conservation of momentum. Initially, the total momentum is: (20 kg x 10 m/s) + (5 kg x 0 m/s) = 200 kg m/s.After the collision, the combined mass is 25 kg, so using the conservation of momentum, we have: 25 kg x V = 200 kg m/s, which gives V = 8 m/s.Now, calculate the kinetic energy of the composite mass using: K.E = 1/2 x 25 kg x (8 m/s)2 = 800 J.Therefore, option B is correct. Options A, C, and D are incorrect as they do not align with the results from the correct application of the conservation of momentum and subsequent kinetic energy calculation.
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