If the echo (the reflected sound) reaches your ear less than about
0.1 second after the original sound, your brain doesn't separate them,
and you're not aware of the echo even though it's there.
If the echo comes from, say, a wall, 0.1 second means you'd have to be
about 17 meters away from the wall. If you're closer than that, then the
echo reaches you in less than 0.1 second and you're not aware of it.
A. 30 meters . . .
No. You hear that echo easily
B. you're standing within range of both sounds . . .
No. You hear that echo easily, if you're at least 17 meters from the wall.
C. less than 0.1 second later . . .
That's it. The echo is there but your brain doesn't know it.
D. 21.5 meters
No. You hear that echo easily.
It is B. false that an instrument used to detect a static electric charge is called an ammeter. It is actually called an electroscope. Ammeter measures current.
dimension = 30.0 m ✕ 15.0 m ✕ 5.0 m.
density = 1.20 kg/m3
(a)volume = lenght * breadth * height
= 30 * 15 * 5
= 2250 metre cube = 2.25 cubic meter
(b) mass of air = density * volume
mass of air = 1.2 * 2250
mass of air = 2700kg
weight = mass * 9.8
= 2700 * 9.8
= 26,460 N
- The definition of Density is the amount of matter in a given space, or volume
- Density = mass/volume
- units for density kg/m^3
- Density of water 1g/ml
- Salt water is denser that is why don't sink as easily.
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A sphere is charged with electrons to −9 × 10−6 C. The value given is the total charge of all the electrons present in the sphere. To calculate the number of electrons in the sphere, we divide the the total charge with the charge of one electron.
N = 9 × 10−6 C / 1.6 × 10−19 C
N = 5.6 x 10^13
<span>The systems of the body involved in preparing and eating a sandwich are :
</span>The skeletal, muscular, and digestive system. They are all directly involved in eating and preparing a sandwich.
