Answer : The original mass of the sample was 0.581 grams.
Explanation :
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time passed by the sample = 5.00 years
a = original or initial amount of the reactant = ?
a - x = amount left after decay process = 0.302 g
Now put all the given values in above equation, we get


Therefore, the original mass of the sample was 0.581 grams.
Answer:
Density of the mixture = 855.56kgm-3
Explanation:
Density = Mass / Volume
Volume of Liquid X = 0.5m³
Density of Liquid X = 900kgm-3
Mass of Liquid X = Density × Volume
= 900kgm-3 × 0.5m³ = 450kg
Volume of Liquid Y = 0.4m³
Density of Liquid Y = 800kgm-3
Mass of Liquid Y = Density × Volume
= 800kgm-3 × 0.4m³= 320kg
As X and Y are mixed, we add their masses and volumes together:
Mass = 770kg
Volume = 0.9m³
Now we can find the density of the mixture:
Density = 770kg / 0.9m³ = 855.56kgm-3 (rounded to the 2nd decimal)
Answer:
204 m
Explanation:
When the marble is dropped from a certain height, its gravitational potential energy converts into kinetic energy. So the kinetic energy gained is equal to the variation of gravitational potential energy:

where
m is the mass of the marble
g = 9.8 m/s^2 is the acceleration of gravity
is the change in height
In this problem, we have
m = 50 g = 0.05 kg

Solving the formula for
, we find the necessary height from which the marble should be dropped:

first one is true, there's no net force acting on it thats greater than another or making it unbalanced, if there was the object would be in some kind of motion
All scientist use meters, that way scientist can share information across country without needing to convert the data.
3. is air resistance
4. The large rock