<h2>Let us find the efficiency : Ans = 0.6</h2>
Explanation:
we know :
efficiency = output/input
We also know that :
output = m x g x h
where :
m = mass of body
g = acceleration due to gravity
h = height of body from floor
Thus, output = 0.6 x 10 x 1.2 = 7.2J
Similarly ,input = 0.6 x 10 x 2 = 12J
Thus efficiency = 7.2/12 = 0.6
<h2>
Dimension for cheap enclose = 32.45 ft x 23.52 ft</h2>
Explanation:
Area of rectangular field, A = 830 ft²
Length = l
Width = w
So we have
l x w = 830

Fencing costs $2 per foot for two opposite sides, and $3 per foot for the other two sides.
Cost for fencing, C = 2 x 2 x w + 3 x 2 x l = 4 w + 6 l

For minimum cost we have derivative is zero

Dimension for cheap enclose = 32.45 ft x 23.52 ft
Answer:
2.4564 m/s
Explanation:
Number of waves in 1 second

This is the frequency 0.267 Hz
The distance mentioned in the question is the
= Wavelength = 9.2 m
The speed of wave is



The speed of the wave is 2.4564 m/s
Answer:
60 rad/s
Explanation:
∑τ = Iα
Fr = Iα
For a solid disc, I = ½ mr².
Fr = ½ mr² α
α = 2F / (mr)
α = 2 (20 N) / (0.25 kg × 0.30 m)
α = 533.33 rad/s²
The arc length is 1 m, so the angle is:
s = rθ
1 m = 0.30 m θ
θ = 3.33 rad
Use constant acceleration equation to find ω.
ω² = ω₀² + 2αΔθ
ω² = (0 rad/s)² + 2 (533.33 rad/s²) (3.33 rad)
ω = 59.6 rad/s
Rounding to one significant figure, the angular velocity is 60 rad/s.
<h2>
Answer: The half-life of beryllium-15 is 400 times greater than the half-life of beryllium-13.</h2>
Explanation:
The half-life
of a radioactive isotope refers to its decay period, which is the average lifetime of an atom before it disintegrates.
In this case, we are given the half life of two elements:
beryllium-13: 
beryllium-15: 
As we can see, the half-life of beryllium-15 is greater than the half-life of beryllium-13, but how great?
We can find it out by the following expression:

Where
is the amount we want to find:


Finally:

Therefore:
The half-life of beryllium-15 is <u>400 times greater than</u> the half-life of beryllium-13.