The correct answer is:
<span>Point charges must be in a vacuum.
In fact, the usual form for of the Coulomb's law is:
</span>
<span>where
</span>
is the permittivity of free space
<span>q1 and q2 are the two charges
q is the separation between the two charges
However, this formula is valid only if the charges are in vacuum. If they are in a material medium, the law is modified as follows:
</span>
where
is the relative permittivity, which takes into account the dielectric effects of the material.
frequency=4Hz
wavelength=5m
amplitude=1/2×2=1m
period=1/frequency
1/4=0.25seconds.
velocity=wavelength×frequency
=5×4
=20m/s
Answer:
The perceived frequency is higher than the actual emitted sound frequency. that means that the received sound waves are of shorter wavelength.
Explanation:
When the source of a sound wave is moving toward the observer, the perceived frequency of the wave changes in relation to the observer producing a change in pitch. The effect is called Doppler effect in honor of the physicist who formulated the physical explanation.
In the case of the sound source approaching the observer, the perceived frequency is higher than that actually emitted by the sound source.
Answer:
How much does a hair weigh in MG?
An average hair (about six inches in length) weighs about 0.2-0.4 milligrams or 0.00015 ounces. A healthy person has anywhere between 80,000 and 120,000 hairs on their head.
Explanation:
Answer:
a) 0.036 J b) 0.036J c) 0.036 d) 1.9m/s e) 0.18 m
Explanation:
Mass of the dart = 0.02kg, the spring was compressed to 6cm
Work needed to compress the spring = 1/2*k*x ^2 where k is the force constant of the spring in N/m, x is the distance it was compressed in m
Work needed to compress the spring = 0.5 * 20* 0.06^2 since 6cm = 6 / 100 = 0.06 m
Work needed to compress the spring = 0.036J
b) the total energy stored in the spring = the work done to compress the spring = 0.036J
c) kinetic energy of the dart as it leaves the the spring = elastic potential energy stored in the spring = the work done in compressing the = 0.036J using the law of conservation of energy; energy is neither created nor destroyed but transformed from one form to another.
d) 1/2mv^2 = 0.036
mv^2 = 0.036*2
v^2 = 0.036*2 / 0.02 = 3.6
v = √3.6 = 1.897 approx 1.9m/s
e) kinetic energy of the dart = work done against gravity to get the body to height h
Work done against gravity = potential energy conserved at height = -mgh g is negative because the motion is upward while gravity acts downward
0.036 = 0.02 * 9.81 * h
0.036 / ( 0.02*9.81) = h
h = 0.18 m
