C. According to the velocity displacement formula: V22 = 2ah', the solution is V2 = 2ah' = 2× 2× 0.25m/s =1m/s;
According to Newton's second law: F-mg=ma,
Solution: f = mg+ma =/kloc-0 /×12n =12n,
Then the instantaneous power of the pulling force F is: p = Fv =12×1w =12w. So, C is correct.
D, according to the conservation of mechanical energy, the kinetic energy of the contact between the object and the nail is 12J, according to the conservation of energy:
mgh2+ 12mv2=fh2,
Alternative data: = 6 10n. Therefore, d is correct.
Therefore: alkaline catalytic decomposition ..
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