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Two cards are drawn one after another with replacement from a well-shuffled standard deck of 52 cards. Let $X$ be the number of aces obtained. Find $P(X=1)+P(X=2)$.
$p=P(\text{ace})=\dfrac{4}{52}=\dfrac{1}{13}$, $q=\dfrac{12}{13}$. Binomial with $n=2$.
$P(X=1)=\binom{2}{1}\cdot\dfrac{1}{13}\cdot\dfrac{12}{13}=\dfrac{24}{169}$
$P(X=2)=\binom{2}{2}\cdot\left(\dfrac{1}{13}\right)^2=\dfrac{1}{169}$
$P(X=1)+P(X=2)=\dfrac{24}{169}+\dfrac{1}{169}=\dfrac{25}{169}$
Three consecutive integers have a sum of $-84$. Compare:
Quantity A: The smallest of the three integers
Quantity B: $-28$
Let the three consecutive integers be $n-1,\ n,\ n+1$.
$(n-1) + n + (n+1) = 3n = -84$
$n = -28$
The three integers are $-29,\ -28,\ -27$.
The smallest is $-29$.
Quantity A $= -29$, Quantity B $= -28$.
Since $-29 < -28$, Quantity B is greater.
Thermal strain produced in the rod if it were free to expand is $\frac{\Delta L}{L} = \alpha \Delta T$.
Young's modulus is defined as $Y = \frac{\text{Stress}}{\text{Strain}} = \frac{F/A}{\Delta L/L}$.
Substituting the thermal strain:
$Y = \frac{F/A}{\alpha \Delta T} = \frac{F}{A\alpha \Delta T}$
Assuming the gas is monoatomic (as is standard in such problems unless specified otherwise), the internal energy $U$ is given by:
$U = \frac{3}{2} nRT = \frac{3}{2} PV$
$U = \frac{3}{2} \times (3 \times 10^6 \text{ Pa}) \times (2 \text{ m}^3)$
$U = 3 \times 3 \times 10^6 = 9 \times 10^6 \text{ J}$.
The three slabs are placed side-by-side (parallel combination), each occupying one-third of the area $A/3$ and the full separation $d$.
Total capacitance:
$C = \frac{\varepsilon_0 (A/3)}{d}(K_1 + K_2 + K_3) = \frac{\varepsilon_0 A}{3d}(10+12+14) = \frac{36\varepsilon_0 A}{3d} = \frac{12\varepsilon_0 A}{d}$
For a single dielectric $K$:
$C = \frac{K\varepsilon_0 A}{d}$
$\Rightarrow K = 12$
The equivalent dielectric constant is simply the arithmetic mean: $(10+12+14)/3 = 12$.
The internal energy $U$ of a monoatomic gas is $U = \frac{3}{2} nRT = \frac{3}{2} PV$.
First, find the volume $V$ using mass and density: $V = \frac{\text{mass}}{\text{density}} = \frac{2}{8} = 0.25 \text{ m}^3$.
$U = \frac{3}{2} \times (4 \times 10^4) \times 0.25 = 1.5 \times 10^4 = 15000 \text{ J}$.
The order of magnitude is $10^4 \text{ J}$.
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