Answer:
The natural phenomenon used to describe the length of a meter is the speed of light. The length of a meter is the length a light path travels in 1/(299792458) seconds through a vacuum.
The definition is better due to the uncertainty involved in the use of the length of a standard meter stick because the length of the meter stick could change due to atmospheric conditions from place to place
Explanation:
Answer:
Cultural Pest Control.
Explanation:
The cultural pest control is one of the oldest methos of pest control. This form of pest control is less practiced these days since curative form of pest control methods have been invented. The cultural pest control method is a preventive method of managing pest population. This pest control method takes long days of planning and execution.
<u>In this form of pest control method, the farmer had to change the timings of his farming operations in his field. This method requires careful timing in seeding and planting. This method of pest controlling requires knowledge and skills of fields</u>.
Thus the correct answer is the third option.
Answer:
Explanation:
From the periodic table, the element designated as Sn is tin. Sn is derieved from a latin name of the metal called Stanum
Selenium Se is a group 6 element. It belongs to the same group with oxygen, sulfur and tellurium. This substance has an atomic weight of 78.96g/mol
Oxygen is a group 6 element with an atomic mass of 16. The atomic mass is the number of protons in the nucleus of this atom.
Answer:
100N
Explanation:
Given parameters:
Mass of the bowling ball = 20kg
Acceleration = 5m/s²
Unknown:
Amount of force applied = ?
Solution:
To solve this problem, we apply newton's second law of motion.
Force = mass x acceleration
Now insert the parameters and solve;
Force = 20 x 5 = 100N
Given, half life of a certain radioactive element = 800 years.
Amount of substance remaining at time t = 12.5%
Lets consider the initial amount of the radioactive substance = 100%
Using the half life equation:
A = A₀(1/2)^t/t₁/₂
where A₀ is the amount of radioactive substance at time zero and A is the amount of radioactive substance at time t, and t₁/₂ is the half-life of the radioactive substance.
Plugging the given data into the half life equation we have,
12.5 = 100 . (1/2)^t/800
12.5/100 = (1/2)^t/800
0.125 = (0.5)^t/800
(0.5)^3 = (0.5)^t/800
3 = t/800
t = 2400 years
Thus the object is 2400 years old.
