Answer:
284 m
Explanation:
According to engineeringtoolbox(dot)com the speed of compressive sound in concrete is 3700 m/s
The speed of sound in standard air is 343 m/s
If t is the time in seconds of sound travel through the concrete and d is the distance
d = 3700t
d = 343(t + 0.75)
3700t = 343t + 257
3,357t = 257
t = 0.07663 s
d = 3700(0.07663) = 284 m
d = 343(0.07663 + 0.75) = 284 m
The equation for kinetic energy is,
Ke = (1/2)mv^2.
You're given a kinetic energy of 790 joules, and a speed of 1.6 m/s. Plugging these values into the equation, we get,
790 = (1/2)(1.6)^2(m).
Solving for m, we get,
m = (790)/(0.5(1.6)^2).
I'll let you crunch out those numbers for yourself :D
If you have any questions, feel free to ask. Hope this helps!
Answer:
D. Hotel 3 because they will experience beach erosion
Explanation:
A beach groin is a man made structure which is used to protect the beach from sand erosion. It makes the water current to deviate in the other direction thus preventing the beach in the groin area to be eroded.
In the context, constructing a groin by Hotel 2 will prevent beach erosion in its area but this will lead to the soil erosion for the beach in front of hotel 3, thus affecting hotel 3. So Hotel 3 can sue Hotel 2 and stop the groin being constructed by the Hotel 2.
Hence the correct option is (D).
Answer:
Apparent
The key discovery about Cepheid variable stars that led in the 1920s to the resolution of the question of whether spiral "nebulae" were separate and distant galaxies or part of the Milky Way Galaxy was the direct relationship between the pulsation period and the absolute brightness or luminosity of the Cepheid variables. A measurement of apparent brightness of a variable star could then be used to determine the distance to the "nebula" containing it.
Explanation:
A variable star is a star with changing apparent brightness. The changes can occur over years or in a fraction of seconds. For example the sun whose energy output varies by approximately 0.1 percent of its magnitude, over an 11-year solar cycle. This variable(apparent brightness) can be used to determine how far a variable star is (distance). Therefore, a measurement of apparent brightness of a variable star could then be used to determine the distance to the "nebula" containing it.
Answer:
625 piece.
Explanation:
Let n be the required no of piece
200 litre = 200 x 10⁻³ m³ = 200 x 10⁻³ x 10³ kg = 200 Kg
mass of ice piece = n x 30 x /1000
Heat lost by ice pieces = (n x 30) / 1000 x ( 80 + 1 x 16⁰C)
Heat gained by water = 200 x 1 x 9⁰C
Heat lost = Heat gained
(n x 30) /1000 x ( 80 + 16 ) =200 x 9
2.88 n = 1800
n = 625