Answer:
16Hz
Explanation:
Given parameters:
Speed of sound = 400m/s
Wavelength = 25m
Unknown:
Frequency of the wave = ?
Solution:
To solve this problem;
V = F ∧
V is the velocity
F is the frequency
∧ is the wavelength
400 = F x 25
F = 16Hz
Electric force from electomagnetic force and force of gravity from gravitational force
Answer:
5 mg, 
Explanation:
First of all, let's rewrite the mass in grams using scientific notation.
we have:
m = 0.005 g
To rewrite it in scientific notation, we must count by how many digits we have to move the dot on the right - in this case three. So in scientific notation is

If we want to convert into milligrams, we must remind that
1 g = 1000 mg
So we can use the proportion

and we find

as it is given that


now we will have

now the magnitude of this vector is given as


now to find the direction we can use




Microscope lenses , glasses for people who can't see faraway as well and microwave lenses which reflect electromagnetic radiation. Oh and curved mirrors.