Answer:
Explanation:
Near point = 56 cm .
near point of healthy person = 25 cm
person suffers from long sightedness
convex lens will be required .
object distance u = 25 cm
image distance v = 56 cm
both will be negative as both are in front of the lens.
lens formula
I/v - 1 / u = 1/f
- 1/56 +1/25 = 1/f
- .01785 + .04 = 1/f
1/f = .02215
f = 45.15 cm .
Answer:
Q1: 3.2km
Q2: 4.8K
Explanation:
Q1:
So db is the distance of bird, and dr is the distance of runner
db = 2vr and the distance of bird is going to be 2 times greater than the runner.
formulas: db = 2vr & db = 2dr
- db = 2dr
- L + (L - x) = 2x
- 2L - x = 2x
- 2L = 3x
- x =
L
Insert it in x =
L
(2.4km) = 1.6km
Now we use formula db = 2dr
- db = 2L - x
- db = 2(2.4km) - 1.6km
- <u>db = 3.2km</u>
Q2:
Formulas: Vr = L /Δt & Vb = db/Δt
- Vr = L/ Δt ⇒ Δt =
![\frac{L}{Vr}](https://tex.z-dn.net/?f=%5Cfrac%7BL%7D%7BVr%7D)
![\frac{2.4km}{6.8km/hr}](https://tex.z-dn.net/?f=%5Cfrac%7B2.4km%7D%7B6.8km%2Fhr%7D)
![\frac{6}{17}hr](https://tex.z-dn.net/?f=%5Cfrac%7B6%7D%7B17%7Dhr)
(Km cancel each other)
- Vb = db/Δt ⇒ db = VbΔt
- 13.6km/hr
![(\frac{6}{17}hr )](https://tex.z-dn.net/?f=%28%5Cfrac%7B6%7D%7B17%7Dhr%20%29)
- <u>4.8km</u>
(hr cancel each other)
Hope it helps you :)
The answer is C, individuals copy works to view at a later time.