A. The formula for mean free time is:
t = V/(4π√2 r²vN)
where
N = 1×10¹⁶ molecules (per m³)
V = 1 m³
r = 111×10⁻⁷m (atomic radius of silicon)
Let's solve for v first:
v = √(3RT/M) = √(3(8.314 m³·Pa/mol·K)(25 + 273 K)/28.1 g/mol Si)
v = 16.26 m/s
t = (1 m³)/(4π√2 (111×10⁻⁷m)²(16.26 m/s)(1×10¹⁶ molecules))
<em>t = 2.81×10⁻9 s</em>
<em>Pure silicon has a high resistivity relative to copper because copper is a conductor, while silicon is a semi-conductor. </em>
Answer:
because some waste heat is always produced produced in a heat engine.
Explanation:
the fraction of heat input that is converted to a net work output is a measure of the performance of the heat engine and is called the thermal efficiency.Since the machine does not contain a source of energy ,nor can it store energy ,from this conversation of energy the power output of machine can never be greater than its input,so efficiency can be less than 100%.
Newton's second law of motion. F = m a .
Answer:
Explanation:
Rate of change of pressure with respect to heigh
= k p ( given )
= k dh
Integrating on both sides
∫ = ∫ k dh
lnp = kh + c , c is a constant
when h = 1000 m , p = 89.1 k Pa
ln 89.1 = 1000 k + c -------------- (1)
when h = 0 , p = 103.6 k Pa
ln 103.6 = 0 x k + c
c = ln 103.6
Putting it in quation (1)
ln 89.1 = 1000 k + ln103.6
ln = 1000k
k =
= - .15 x 10⁻³
lnp = - .15 x 10⁻³ h + ln 103.6
when h = 3000
lnp = - .15 x 10⁻³ x 3000 + ln 103.6
= - .45 +4.64
= 4.2
p = 66.68 k Pa
b )
when h = 6358
lnp = - .15 x 10⁻³ x 6358 + ln 103.6
= - .9537 + 4.64
= 3.6863
39.9 k Pa.
Answer:
a) 3.13 m/s
b) 2.8 m/s
c) 0.485 m
d) 2.8 m/s
Explanation:
a) PE @ A = KE @ B
mgh = ½ mv²
v = √(2gh)
v = √(2 × 9.8 m/s² × 0.50 m)
v = 3.13 m/s
b) PE @ A = KE @ C + Work done by friction
mgh = ½ mv² + Fd
mgh = ½ mv² + mgμd
gh = ½ v² + gμd
g (h − μd) = ½ v²
v = √(2g (h − μd))
v = √(2 × 9.8 m/s² (0.50 m − 0.1 × 1 m))
v = 2.8 m/s
c) KE @ C = EE
½ mv² = ½ kx²
mv² = kx²
x = v √(m / k)
x = (2.8 m/s) √(3 kg / 100 N/m)
x = 0.485 m
d) Since there's no friction between point C and the spring, the speed is the same as before.
v = 2.8 m/s