1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Masja [62]
3 years ago
11

A nearsighted person cannot see objects further away than 10 m clearly. This person wants to be able to see objects 300 m away w

ithout trouble. What is the focal length of the lens you would prescribe? (Ignore the distance between the person’s eye and the lens.)
a. 9.7 m
b. – 9.7 m
c. No such lens can be prescribed.
d. 10.3 m
e. – 30 m
f. 30 m
g. – 10.3 m
Physics
2 answers:
k0ka [10]3 years ago
5 0

Answer:

d. 10.3 m

Explanation:

For a nearsighted person,

1/f = (1/v)+(1/u).................... Equation 1

f = focal, v = image distance, u = object distance.

f = vu/(v+u)................. Equation 2

Given: v = -10 m, u = 300 m

Substitute into equation 2

f = (-10×300)/(-10+300)

f = -3000/290

f = -10.34 m

therefore a concave lens of focal length 10.34 m is  required.

The right option is d. 10.3 m

icang [17]3 years ago
4 0

Answer:

d.-10.3m

Explanation:

Note for short sightedness the focal length is negative

Let do be object distance=10m

And di= image distance=-300m

Using lens formula

F=do*di/do-di= 10*300/10-300=-10.3m

You might be interested in
How to do projects on newton’s law
emmainna [20.7K]
Do swimming which make Newtons Third Law
8 0
2 years ago
Air at 400 kPa, 980 K enters a turbine operating at steady state and exits at 100 kPa, 670 K. Heat transfer from the turbine occ
Angelina_Jolie [31]

Answer:

a). \frac{\dot{W}}{m}= 311 kJ/kg

b). \frac{\dot{\sigma _{gen}}}{m}=0.9113 kJ/kg-K

Explanation:

a). The energy rate balance equation in the control volume is given by

\dot{Q} - \dot{W}+m(h_{1}-h_{2})=0

\frac{\dot{Q}}{m} = \frac{\dot{W}}{m}+m(h_{1}-h_{2})

\frac{\dot{W}}{m}= \frac{\dot{Q}}{m}+c_{p}(T_{1}-T_{2})

\frac{\dot{W}}{m}= -30+1.1(980-670)

\frac{\dot{W}}{m}= 311 kJ/kg

b). Entropy produced from the entropy balance equation in a control volume is given by

\frac{\dot{Q}}{T_{boundary}}+\dot{m}(s_{1}-s_{2})+\dot{\sigma _{gen}}=0

\frac{\dot{\sigma _{gen}}}{m}=\frac{-\frac{\dot{Q}}{m}}{T_{boundary}}+(s_{2}-s_{1})

\frac{\dot{\sigma _{gen}}}{m}=\frac{-\frac{\dot{Q}}{m}}{T_{boundary}}+c_{p}ln\frac{T_{2}}{T_{1}}-R.ln\frac{p_{2}}{p_{1}}

\frac{\dot{\sigma _{gen}}}{m}=\frac{-30}{315}+1.1ln\frac{670}{980}-0.287.ln\frac{100}{400}

\frac{\dot{\sigma _{gen}}}{m}=0.0952+0.4183+0.3978

\frac{\dot{\sigma _{gen}}}{m}=0.9113 kJ/kg-K

5 0
3 years ago
which of the following describes water changing from liqyid to solid, please give me a proof for this question please i really n
Fittoniya [83]
The answers A, this is because Ice is originally water and when water goes below it's freezing point it turns into ice
4 0
3 years ago
Read 2 more answers
What is the speed of light in a vacuume?
-Dominant- [34]

The speed of light in vacuum is exactly

299,792,458 meters per second.

That's so exact that it's the official scientific definition of a "meter".

The number doesn't t change even if the flashlight or other light source is moving.

5 0
2 years ago
One major disadvantage of breeder reactors is that they can do which of the following? Select one:a.explodeb.leak radioactivityc
zimovet [89]

definition of breeder reactors.

These are a type of nuclear reactors which produce more fissile material than they consume

Advantages: Breeder reactors produce Pu-239 which can be extensively used as a nuclear fuel. Also, Pu-239 can absorb neutron to form Pu-240, which is another fertile material.[1]

8 0
1 year ago
Other questions:
  • It would be really helpful if u help me solving this question. PLEASE!!!
    7·1 answer
  • Which of the following statements best describes the second law of
    12·1 answer
  • You venture out on a cold winter morning to warm up your vehicle. You have layers of cotton/polyester blend clothes on and from
    11·1 answer
  • To balance a chemical equation we use______. <br> -coefficients <br> -subscripts
    15·1 answer
  • Which of these changes would solidify a substance?
    7·1 answer
  • A 6kg rock rolls down a hill with a momentum of 12kg m/s . Work out the velocity of the rock
    8·2 answers
  • A gas expands against a constant external pressure of 2.00 atm until its volume has increased from 6.00 to 10.00 L. During this
    5·1 answer
  • Explane Information-processing approach
    5·1 answer
  • Which statement best describes what happens during a solar eclipse?
    13·2 answers
  • From
    11·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!