They can't hear an echo in small room because in it the sound can't be reflected back. For an echo of a sound to be heard,the minimum distance between the source of sound and the walls of the roomshould be 17.2 m. Obviously,in asmall room echoes cannot beheard.
Answer: V = 15 m/s
Explanation:
As stationary speed gun emits a microwave beam at 2.10*10^10Hz. It reflects off a car and returns 1030 Hz higher. The observed frequency the car will be experiencing will be addition of the two frequency. That is,
F = 2.1 × 10^10 + 1030 = 2.100000103×10^10Hz
Using doppler effect formula
F = C/ ( C - V) × f
Where
F = observed frequency
f = source frequency
C = speed of light = 3×10^8
V = speed of the car
Substitute all the parameters into the formula
2.100000103×10^10 = 3×10^8/(3×10^8 -V) × 2.1×10^10
2.100000103×10^10/2.1×10^10 = 3×108/(3×10^8 - V)
1.000000049 = 3×10^8/(3×10^8 - V)
Cross multiply
300000014.7 - 1.000000049V = 3×10^8
Collect the like terms
1.000000049V = 14.71429
Make V the subject of formula
V = 14.71429/1.000000049
V = 14.7 m/s
The speed of the car is 15 m/s approximately
Answer: 0.0146m
Explanation: The formula that defines the velocity of a simple harmonic motion is given as
v = ω√A² - x²
Where v = linear velocity, A = amplitude = 1.69cm = 0.0169m, x = displacement.
The maximum speed of a simple harmonic motion is derived when x = A, hence v = ωA
One half of maximum speed = speed of motion
3ωA/2 = ω√A² - x²
ω cancels out on both sides of the equation, hence we have that
A/2 = √A² - x²
(0.0169)/2 = √(0.0169² - x²)
0.00845 = √(0.0169² - x²)
By squaring both sides, we have that
0.00845² = 0.0169² - x²
x² = 0.0169² - 0.00845²
x² = 0.0002142
x = √0.0002142
x = 0.0146m
Answer:
Electromagnetic force
Explanation:
There are four fundamental forces in nature:
- Gravity: it is the force that is exerted between any objects with mass. It is the weakest of all forces, so it is only relevant at planetary scales. It is always attractive, and it has an infinite range.
- Electromagnetic force: it is the force exerted between charged objects and between magnets (it is responsible for electric fields and magnetic fields). It is the 2nd strongest force, and it is the force that holds atoms in a molecule together. It can be attractive or repulsive, and it has an infinite range.
- Strong nuclear force: it is the strongest of all forces. It is responsible for holding the nucleons together inside the nucleus, and it is attractive. It has a very limited range (
), so it is relevant only at very small scales
- Weak nuclear force: it is the force responsible for radioactive decays and neutrino interactions. It also has a very short range (
Looking at all these definitions, we see that the term that defines the force that acts between charged particles is the electromagnetic force.
