If momentum is increased by 20% then K.E. increases by _.
Correct answer: A. 0.44
- A. 0.44
- B. 0.55
- C. 0.66
- D. 0.77
Explanation
The increase in momentum is given as 20%, which can be expressed as a factor of 1.2. Therefore, the new momentum is 1.2 times the original momentum. Now, the kinetic energy (K.E.) is given by the equation K.E. = (p2)/(2m), where p is the momentum and m is the mass of the object. If the momentum is increased by a factor of 1.2, then the new kinetic energy is: K.E.' = ((1.2p)2}/(2m) = (1.44p2)/(2m) The increase in kinetic energy is given by: ΔK.E. = K.E.' - K.E. ΔK.E. = (1.44p2)/(2m) - (1p2)/(2m) ΔK.E. = (0.44p2)/(2m) Since p2 and 2m are constants, we can see that the increase in kinetic energy is directly proportional to p2/(2m), which is the initial kinetic energy. Therefore, the increase in kinetic energy is: ΔK.E./K.E. = (0.44p2)/(2m) / (p2)/(2m) = 0.44 Hence, the increase in K.E. is 0.44
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Kinetic energy is the energy of motion, given for a nonrelativistic object by K = ½mv², so it depends on mass and the square of speed. Questions connect kinetic energy with work through the work energy theorem, calculate changes in kinetic energy, and distinguish it from momentum and potential energy.
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