Answer:
(a) hypermetropia
(b) convex lens
(c) 133.33 cm
(d) - 21.05 cm
Explanation:
(a) As she is old age, so she is suffering from hypermetropia.
(b) It is the defect due to which a person is not able to see the nearby objects clearly, so it is cured by convex lens of suitable focal length.
(c) Power, P = + 0.75 D
Focal length is the reciprocal of power of lens.
f = 1/ P = 1/0.75
f = 133.33 cm
(d) v = -25 cm, f = 133.3 cm
use lens equation



u = - 21.05 cm
Explanation:
The vertical component the velocity of the projectile is 15 m/s x sin 30 = 7.5 m/s.
The body is accelarating downwards at 10 m/s^2.
This means that every second its upward velocity reduces by 10 m/s.
So if the body is travelling upwards at 7.5 m/s then how long does it take for the velocity to become 0?
(7.5 m/s) / (10 m/s^2) = 0.75 s
Answer:
P=4801.5
Explanation:
Given :
work done = W = 100,832 J
time = 21.0 sec
Find:
P = ?
Formula:
P = W/t
Solution:
P = W/t
P = 100,832/21.0
= 4801.52 J/s or Watts
When boat is sunk into the liquid the net buoyancy on the boat is counterbalanced by weight of the boat
So here weight of the boat = Buoyancy force
let say boat is sunk by distance "h"
now we can say


now by above force balance equation we can write




so boat will sunk by total 5 mm distance
50km / 2.5 = 20 km per hour