<u>Answer :</u>
(a) d = 0.25 m
(b) d = 0.5 m
<u>Explanation :</u>
It is given that,
Frequency of sound waves, f = 686 Hz
Speed of sound wave at 
is, v = 343 m/s
(1) Perfectly destructive interference occurs when the path difference is half integral multiple of wavelength i.e.
........(1)
Velocity of sound wave is given by :
Hence, when the speakers are in phase the smallest distance between the speakers for which the interference of the sound waves is perfectly destructive is 0.25 m.
(2) For constructive interference, the path difference is integral multiple of wavelengths i.e.
( n = integers )
Let n = 1
So, 
Hence, the smallest distance between the speakers for which the interference of the sound waves is maximum constructive is 0.5 m.
The approximate height of the tsunami in Alaska in 1958 is 1720ft
Answer;
It allows the muscles time to heal.
Explanation;
-It is very important to rest muscles between workouts. In fact, resistance training breaks down muscles causing microscopic tears. It is only during rest when the muscle-building process is stimulated and the regeneration of new tissue occurs.
-But when muscles are not allowed adequate rest and recover time, the regeneration process cannot occur. This can have several side effects such as increased soreness, decreased strength and performance, and may lead to injury.
According to the law of conservation of energy,
A. an object loses most of its energy as friction
<u>B. the total amount of energy for a system stays the same</u>
Energy is never lost due to the law of conservation
C. the potential energy of an object is always greater than its kinetic energy
D. the kinetic energy of an object is always greater than its potential energy
Answer:
<em>2.753*10^-11N</em>
Explanation:
According to Newton's law of gravitation, the force between the masses is expressed as;
F = GMm/d²
M and m are the distances
d is the distance between the masses
Given
M = 3.71 x 10 kg
m = 1.88 x 10^4 kg
d = 1300m
G = 6.67 x 10-11 Nm²/kg
Substitute into the formula
F = 6.67 x 10-11* (3.71 x 10)*(1.88 x 10^4)/1300²
F = 46.52*10^(-6)/1.69 * 10^6
F = 27.53 * 10^{-6-6}
F = 27.53*10^{-12}
F = 2.753*10^-11
<em>Hence the gravitational force between the asteroid is 2.753*10^-11N</em>
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