Does this help?
When an object is
immersed in a fluid (in this case water, but may include both liquids and
gases) the fluid exerts an upward force on the object which is called buoyancy
force or <span>up-thrust. Archimedes’ Principle states that the buoyant
force (upward push or force) applied to an object is equal to the weight of the fluid that the object takes the space of by
that object. Thus when an object is
placed in water the rise in the water level is dictated by the mass of that
object.</span>
<span>
</span>
<span>So for example if you fill a bucket with water and you drop a stone in that bucket, if you measure the weight of the water that overflows from the bucket due to the stone being dropped into the bucket is equivalent to the pushing force that the water has on the stone (as the stone drops to the bottom of the bucket the water is pushing it to stay afloat but the rock is more dense than water and as such its downthrust exceeds water's upthrust).</span>
The indicated data are of clear understanding for the development of Airy's theory. In optics this phenomenon is described as an optical phenomenon in which The Light, due to its undulatory nature, tends to diffract when it passes through a circular opening.
The formula used for the radius of the Airy disk is given by,

Where,
Range of the radius
wavelength
f= focal length
Our values are given by,
State 1:



State 2:



Replacing in the first equation we have:


And also for,


Therefor, the airy disk radius ranges from
to 
speed of the car = 27 m/s
speed of truck ahead = 10 m/s
relative speed of car with respect to truck

relative deceleration of car

now the distance before they stop with respect to each other is given by



so it will come at the same speed of truck after 20.6 m distance and hence it will not hit the truck as the distance of the truck is 25 m from car
Part b)
Distance traveled by car before it stops is given by



so it will stop after it will cover total 52.1 m distance
Part c)
time taken by the car to stop



now the distance covered by truck in same time

now after the car will stop its distance from the truck is

<em>so the distance between them is 11.5 m</em>
If the object is kept in between the principle axis and the focus but some what nearer to the focus then we will get the enlarge,erect,and real image.