Katniss vs Clove
In the Hunger Games, teens fight against each other to survive. One girl called Clove, threw 10 knives at me, each weighing 100g and each knife's speed was 9 m/s. My arrows weigh 150g, but I can only shoot at 6 m/s speed. How many minimum arrows do I need to shoot, to overcome the overall momentum of the knives?
(Remember, I said overcome, not equal the momentum)
(Ignore forces of gravity and air friction)
(Assume that all knives and arrows hit each other, and there are no disturbances)
The answer is 11.
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1 solution
Clove's weapon's overall momentum will be 1 0 × 0 . 1 × 9 = 9 s N (10 knives, 0.1 kgs and 9 m/s)
My weapons overall momentum will be x × 0 . 1 5 × 6 = ( 0 . 9 × x ) s N (x arrows, 0.15 kgs and 6 m/s)
If x is the number of arrows I shoot, then x has to be greater than 10 to make the momentum of my arrows greater than the momentum of Clove's knives. As these are arrows, we cannot use decimal values. Thus the answer is 1 1