Question: How fast was the arrow moving before it joined the block?
Answer:
The arrow was moving at 15.9 m/s.
Explanation:
The law of conservation of energy says that the kinetic energy of the arrow must be converted into the potential energy of the block and arrow after it they join:
where 
is the mass of the arrow, 
is the mass of the block, 
of the change in height of the block after the collision, and 
is the velocity of the arrow before it hit the block.
Solving for the velocity , we get:
and we put in the numerical values
,
and simplify to get:
The arrow was moving at 15.9 m/s
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. The gas is formed in the reaction is Carbon dioxide. 
is formed.
The change which happened in this reaction is a chemical change.
Since, in chemical change we can't bring a substance to it's actual form how it was in earlier.
Examples: burning of paper is chemical, since we can't get the fine paper again after it is burnt.
Thus, the above reaction is also a chemical change, since we can't get back the lemon juice how it was earlier.
Answer:
The mass of Ar is 36.91g
Explanation:
The gas mixture consist of Neon(Ne) and Argon(Ar)
Partial pressure of Ar = total pressure of mixture - partial pressure = 4 - 0.3 = 3.7 atm
Mole fraction of Ar = partial pressure of Ar ÷ total pressure of mixture = 3.7/4 = 0.925
Mass of Ar = 0.925 × molecular weight of Ar = 0.925 × 39.9 = 36.91g
Choices 'C' and 'D' are both correct.
(Except in 'C', changing the temperature from 1°C to 3°C is not usually
described as 'cooling', and it's not the water's 'mass' that changes. But
water does contract in volume during that change.)
Answer:
im pretty sure nuclear if not nitrogen
Explanation:
