Theories result from several repeated experiments.
Theories explain observations and hypotheses.
Theories may be revised over time.
Explanation:
Scientific theories are purely explanations into an observation and hypothesis. The are general binding explanations that have been developed from several tests.
- Theories are products of different stages of experiments in their own regard.
- For a theory to be accepted by the scientific community, its hypothesis statement must be:
- Testable
- Repeated
- Falsifiable
- Based on new evidence, a theory may be revised with time. One of such is the Dalton's atomic theory with a modern atomic theory version now.
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Answer:
time taken with speed 23 km/h will be 1.8 hours or 1 hour 48 minutes
Explanation:
Given:
Time is inversely proportional to the speed
mathematically,
t ∝ (1/r)
let the proportionality constant be 'k'
thus,
t = k/r
therefore, for case 1
time = 3 hr
speed = 14 km/hr
3 = k/14
also,
for case 2
let the time be = t
r = 23 km/h
thus,
we have
t = k/23
on dividing equation 2 by 1
we get
or
or
t = 1.8 hr = or 1 hour 48 minutes ( 0.8 hours × 60 minutes/hour = 48 minutes)
This is an interesting (read tricky!) variation of Rydberg Eqn calculation.
Rydberg Eqn: 1/λ = R [1/n1^2 - 1/n2^2]
Where λ is the wavelength of the light; 1282.17 nm = 1282.17×10^-9 m
R is the Rydberg constant: R = 1.09737×10^7 m-1
n2 = 5 (emission)
Hence 1/(1282.17 ×10^-9) = 1.09737× 10^7 [1/n1^2 – 1/25^2]
Some rearranging and collecting up terms:
1 = (1282.17 ×10^-9) (1.09737× 10^7)[1/n2 -1/25]
1= 14.07[1/n^2 – 1/25]
1 =14.07/n^2 – (14.07/25)
14.07n^2 = 1 + 0.5628
n = √(14.07/1.5628) = 3
Answer: the most potential energy == 5 kg book, 2 m from the ground= 98 Joules
Explanation:
potential energy = m g h
m = mass
g = acceleration due gravity = 9.8 m/s²
h = distance above ground
1. Pe₁ = 1 kg x 2 m x g = 2 g
2. Pe₂ = 5 kg x 2 m x g = 10 g = 10 kg m x 9,8 m/s² = 98 Joules
3. Pe₃ = 1 kg x 0,5 m x g = 0,5 g
4. Pe₄ = 5 kg x 0.5 m x g = 2,5 g
10 > 2,5 > 2 >0,5
Answer: Density
Explanation: Recall Archimedes Principle. There are two forces acting an object submerged in a liquid: the force of gravity and the (opposite directed) force of buoyancy. The buoyancy is proportional to the mass of the liquid displaced by the submerged part of the object.
Density is the ratio of mass to volume. Therefore if the density of the submerged object is higher than that of the displaced liquid, the net force will point in the direction of the gravity (object will sink). In the opposite case, the net force will point in the direction of the buoyant force (upward) and the object will float.
