Answer:
The rule for kilometers is that every three seconds between a lightning flash and the following thunder gives the distance to the flash in kilometers.
Explanation:
In order to use the rule of thumb to find the speed of sound in meters per second, we need to use some conversion ratios. We know there is 1 mile per every 5 seconds after the lightning is seen. We also know that there are 5280ft in 1 mile and we also know that there are 0.3048m in 1ft. This is enough information to solve this problem. We set our conversion ratios like this:
notice how the ratios were written in such a way that the units got cancelled when calculating them. Notice that in one ratio the miles were on the numerator of the fraction while on the other they were on the denominator, which allows us to cancel them. The same happened with the feet.
The problem asks us to express the answer to one significant figure so the speed of sound rounds to 300m/s.
For the second part of the problem we need to use conversions again. This time we will write our ratios backwards and take into account that there are 1000m to 1 km, so we get:
This means that for every 3.11s there will be a distance of 1km from the place where the lightning stroke. Since this is a rule of thumb, we round to the nearest integer for the calculations to be made easily, so the rule goes like this:
The rule for kilometers is that every three seconds between a lightning flash and the following thunder gives the distance to the flash in kilometers.
Hello there.
<span>It takes 3 minutes to make toast in a 1500 watt toaster. Calculate how much work is done by the toaster.
</span>270,000 J
Answer:
Mass of Little Sister = 44.17 kg
Explanation:
From Newton's second law of motion, the magnitude of force applied on the sled is given by the following formula:
F = ma
where,
F = Force Applied = 120 N
a = Acceleration = 2.3 m/s²
m = Mass of Sled + Mass of Little Sister = 8 kg + Mass of Little Sister
Therefore,
120 N = (2.3 m/s²)(8 kg + Mass of Little Sister)
(120 N)/(2.3 m/s²) = 8 kg + Mass of Little Sister
Mass of Little Sister = 52.17 kg - 8 kg
<u>Mass of Little Sister = 44.17 kg</u>
Answer:
-40 kJ
80 kJ
Explanation:
Work is equal to the area under the pressure vs volume graph.
W = ∫ᵥ₁ᵛ² P dV
2.27) Pressure and volume are linearly related. When we graph P vs V, the area under the line is a trapezoid. So the work is:
W = ½ (P₁ + P₂) (V₂ − V₁)
W = ½ (100 kPa + 300 kPa) (0.1 m³ − 0.3 m³)
W = -40 kJ
2.29) Pressure and volume are inversely proportional:
pV = k
The initial pressure and volume are 500 kPa and 0.1 m³. So the constant is:
(500) (0.1) = k
k = 50
The final pressure is 100 kPa. So the final volume is:
(100) V = 50
V = 0.5
The work is therefore:
W = ∫ᵥ₁ᵛ² P dV
W = ∫₀₁⁰⁵ (50/V) dV
W = 50 ln(V) |₀₁⁰⁵
W = 50 (ln 0.5 − ln 0.1)
W ≈ 80 kJ
Answer:
The statement that best describes nuclear fusion is;
Nuclei combine to form a heavier nucleus, releasing energy
Explanation:
In nuclear fusion, we have the reaction of the nuclei of two or more atoms coming together (combining) to form heavier elements and subatomic particles such as protons and neutrons accompanied by the release or absorption in energy depending on the difference between the mass of the reactants and the products
Some nuclear fusion reaction require an input of energy and such reactions are therefore not spontaneous
The best option is nuclei (two or more nuclei) combine to form a heavier nucleus, releasing energy.
