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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Displacement, velocity and acceleration describe motion, including the horizontal and vertical components of projectile motion. The chapter connects these quantities with Newton's laws, momentum and impulse, then applies conservation of momentum to collisions, distinguishing elastic collisions from inelastic ones.
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