Answer: ok
Explanation:
The molecules in hot air are moving faster than the molecules in cold air. Because of this, the molecules in hot air tend to be further apart on average, giving hot air a lower density. That means, for the same volume of air, hot air has fewer molecules and so it weighs less.
There is no such thing as"cold", in the same way that there is no such thing
as "darkness" or "quietness". "Darkness" is the absence of light, "quietness"
is the absence of sound, and "cold" is the absence of heat.
Tom should have said that insulation <em>keeps the heat in</em> .
Answer:
The maximum height reached by the body is 313.6 m
The time to return to its point of projection is 8 s.
Explanation:
Given;
initial velocity of the body, u = 78.4 m/s
at maximum height (h) the final velocity of the body (v) = 0
The following equation is applied to determine the maximum height reached by the body;
v² = u² - 2gh
0 = u² - 2gh
2gh = u²
h = u²/2g
h = (78.4²) / (2 x 9.8)
h = 313.6 m
The time to return to its point of projection is calculated as follows;
at maximum height, the final velocity becomes the initial velocity = 0
h = v + ¹/₂gt²
h = 0 + ¹/₂gt²
h = ¹/₂gt²
2h = gt²
t² = 2h/g
![t = \sqrt{\frac{2h}{g} } \\\\t = \sqrt{\frac{2\times 313.6}{9.8} }\\\\t = 8 \ s](https://tex.z-dn.net/?f=t%20%3D%20%5Csqrt%7B%5Cfrac%7B2h%7D%7Bg%7D%20%7D%20%5C%5C%5C%5Ct%20%3D%20%5Csqrt%7B%5Cfrac%7B2%5Ctimes%20313.6%7D%7B9.8%7D%20%7D%5C%5C%5C%5Ct%20%3D%208%20%5C%20s)
Answer:
Given, Apparent weight(W₂)=4.2N
Weight of liquid displaced (u)=2.5N
Let weight of body in air = W₁
Solution,
U=W₁-W₂
W₁=4.2=2.5=6.7N
∴Weight of body in air is 6.7N
Answer:
D.300nm
Explanation:
Wavelength = Speed of light / Frequency of light.....
where the speed of light is...(3 × 10^8)
Wavelength = (3 × 10^8)/(1 × 10^15)
Wavelength = 3 × 10^-7
;Wavelength = 300 × 10^-9
Hence its....300 nm