The spherical side mirror on a car is convex and has a radius of curvature of 25 cm. another car is following, 20 m behind the mirror. if the height of the car is 1.6 m, how tall is its image? (a) 5.0 cm (b) 2.0 cm (c) 4.0 cm (d) 0.99 cm

(D) 0.99 cm

Explanation:

Given that the radius of curvature of the mirror is 25 cm.

And another car is following which is behind the mirror of 20 m.

Focal length is half of the radius of curvature and it is negative for convex lens.

Now the mirror formula.

So,

Now

Magnification is,

So,

So, Height of the image

Therefore, the image height is 0.99 cm.

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =