Blue light can knock electrons off a plate, but red light can't
Answer:
A. 1.6 N/cm
Explanation:
spring constant = 21/13 = 1.6 N/cm
Answer:
Electric potential, E = 2100 volts
Explanation:
Given that,
Electric field, E = 3000 N/C
We need to find the electric potential at a point 0.7 m above the surface, d = 0.7 m
The electric potential is given by :


V = 2100 volts
So, the electric potential at a point 0.7 m above the surface is 2100 volts. Hence, this is the required solution.
Answer: 4
The mechanical advantage is the ratio of the force exerted by the object to the force applied to do work on it.
Here, Jeff tried to lift a rock weighing 600 pounds by wedging board under the rock. Jeff who weighs 150 pounds uses all his weight to exert force on lever and lift rock.
Mechanical advantage, 
Therefore, the mechanical advantage that lever provided to Jeff in lifting rock is 4.
Pathogens are microorganisms that cause infectious diseases. Bacteria and viruses are the main pathogens in the world today.
The major problem that pathogen cause in society is that they are the agents of infection and disease.
An infection results when a pathogen invades the body and begins growing within a host. A disease results when tissue function is impaired due to an infection.
Due to diseases, affected people can not work which negatively affects the economy, and the sick may end up dying causing a lot of grief, and robbing society of a father, a mother or child.
The government has to put money aside for health care which would otherwise have been used for other things to help the society.