Answer:
yes
Explanation:
The metal is closer than 20 cm to the magnet which is in the magnetic field.
True. Classifying by similarities is the basis for biological classification.
Answer:

Explanation:
According to question,
Charge 1 and charge 2 are 
The distance between charges is 2 m
We need to find the force with which two positive charges repel. It is called electrostatic force of repulsion. It can be given by :

So, the electric force of repulsion is
.
Answer:
0.786 Hz, 1.572 Hz, 2.358 Hz, 3.144 Hz
Explanation:
The fundamental frequency of a standing wave on a string is given by

where
L is the length of the string
T is the tension in the string
is the mass per unit length
For the string in the problem,
L = 30.0 m

T = 20.0 N
Substituting into the equation, we find the fundamental frequency:

The next frequencies (harmonics) are given by

with n being an integer number and f being the fundamental frequency.
So we get:



14 m/s or 50km/h. See the details in the attached picture.