Answer:
B
Explanation:
Gravity is an invisible force, and so is magnetism and electricity. Friction involves the rubbing of things together to create energy.
Answer:
chemical change because gas formation was observed along with a color change, which indicated that the copper sulfate pentahydrate was transformed into a different substance
Explanation:
i took a test
A radar receiver indicates that a pulse return as an echo in 20 μs after it was sent. The reflecting object would be 3000 m away .
Phenomenon of hearing back our own sound is called an echo. It is due to successive reflection of sound waves from the surfaces or obstacles of large size. To hear an echo, there must be a time gap of 0.1 second in original sound and the reflected sound.
Given
time = 20 μs = 20 *
s
let distance to the reflecting surface be = x
total distance travelled by pulse will be = 2x
speed = 3.0 ×
m/s
distance = speed * time
2x = 3.0 ×
* 20 *
x = 3000 m
The reflecting object would be 3000 m away
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Answer:
3 s.
Explanation:
Echo is defined as the repetition of a sound produced by the reflection of sound waves from an obstructing surface like a wall, mountain etc.
v = f*lambda
Where,
Lambda = wavelength of the wave
f = frequency of the wave = 1/t
v = velocity of the wave.
Distance there and back = initial ditance * 2
= 525 x 2
= 1050.
Time taken, t = lamda/velocity
= 1050 / 350
= 3 s.
So the delay is 3 seconds.
Answer: It is a transverse wave ^^
Explanation: