The acceleration of gravity is
9.8 m/s^2 down.
When an object falls out of a hand, its speed after 1.8s is
(9.8)x(1.8) = 17.6 m/s down.
It doesn't matter what it is, how much it weighs, or how high it was dropped from.
If it's more than 17.6 m/s, then this happened on a different, bigger planet.
If it's less than 17.6 m/s, then it must have hit something on the way down, like some air or something.
Answer
given,
change in enthalpy = 51 kJ/mole
change in activation energy = 109 kJ/mole
when a reaction is catalysed change in enthalpy between the product and the reactant does not change it remain constant.
where as activation energy of the product and the reactant decreases.
example:
ΔH = 51 kJ/mole
E_a= 83 kJ/mole
here activation energy decrease whereas change in enthalpy remains same.
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