<h2>Question: </h2>
The nearpoint of an eye is 151 cm. A corrective lens is to be used to allow this eye to clearly focus on objects 25 cm in front of it. What should be the focal length of this lens?
Answer:
29.96cm
Explanation:
Using the corrective lens, the image should be formed at the front of the eye and be upright and virtual.
Now using the lens equation as follows;
-------------(i)
Where;
f = focal length of the lens
v = image distance as seen by the lens
u = object distance from the lens
From the question;
v = -151cm [-ve since the image formed is virtual]
u = 25cm
Rewrite equation (i) to have;
Substitute the values of v and u into the equation;
f = 29.96cm
The focal length should be 29.96cm
Answer:
Explanation:
Given:
Length of a rope,
Position of Canary on the rope from one end, 
Position of Grackle on the rope from another end, 
Tension in the rope, 
linear mass distribution on the rope, 
We have for the speed of wave on the string:
<em>For canary to be undisturbed we need a node at this location.</em>
<em>Also, at the end close to Canary there must be a node to avoid any change in pattern of vibration.</em>
So,
the distance between Canary and the closer end must be equal to half the wavelength.
∴Wavelength of wave to be produced = 20 m. This will give us nodes at the multiples of 10 and anti-nodes at the multiples of 5.
Now, frequency:
Answer: mg/Cosθ
Explanation:
Taking horizontal acceleration of wedge as 'a'
FCosΘ = FsinΘ
F = mass(m) × acceleration(a) = ma
For horizontal resolution g = 0
Therefore,
Horizontal = Vertical
maCosΘ = mgSinΘ
aCosΘ = gSinΘ
a = gSinΘ/CosΘ
Recall from trigonometry :
SinΘ/Cosθ = tanΘ
Therefore,
a = gtanΘ
Normal force acing on the wedge:
mgCosΘ + maSinΘ - - - - (y)
Substitute a = gtanΘ into (y)
mgCosΘ + mgtanΘsinΘ
tanΘ = sinΘ/cosΘ
mgCosΘ + mgsinΘ/cosΘsinΘ
mgCosΘ + mgsin^2Θ/cosΘ
Factorizing
mg(Cosθ + sin^2Θ/cosΘ)
Taking the L. C. M
mg[(Cos^2θ + sin^2Θ) /Cosθ]
Recall: Cos^2θ + sin^2Θ = 1
mg[ 1 /Cosθ]
mg/Cosθ
Answer:
the final temperature = 74.33°C
Explanation:
Using the expression Q = mcΔT for the heat transfer and the change in temperature .
Here ;
Q = heat transfer
m = mass of substance
c = specific heat
ΔT = the change in temperature
The heat Q required to change the phase of a sample mass m is:
Q = m
where;
is the latent heat of vaporization.
From the question ;
Let M represent the mass of the coffee that remains after evaporation is:
ΔT = 
where;
m = 2.50 g
M = (240 - 2.50) g = 237.5 g
= 539 kcal/kg
c = 1.00kcal/kg. °C
ΔT = 
ΔT = 5.67°C
The final temperature of the coffee is:
ΔT
where ;
= initial temperature = 80 °C
= (80 - 5.67)°C
= 74.33°C
Thus; the final temperature = 74.33°C
Answer:9A
Explanation:
let the last wire be wire C
According to Kirchhoff's rule
the sum of all currents entering a junction must be equal to the sum of all currents leaving a junction
Ic=Ia+Ib
Ic= 4+5
Ic=9A
