Question

Please answer.


No wrong answer
​

Answer 1

Answer:

Heya!

1. c

2. a

3. b

4. b

5. d

6. a

7. c

8. a

9. d

10. c

Answer 2

$\huge \underline{ \underline{ { \cal \: {A}} \large \red{ \tt \: N} \green{ \tt \: S} \blue{ \tt \: W} \orange{ \tt \: E} \purple{ \tt \: R} }} : -$

❶

$\begin{gathered}:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{\theta}\:=\:m} \\ \end{gathered}$

Where,

θ = 45°

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{45^{\circ}}}$

$:\longrightarrow\:\:\bf{8}$

Thus,

➻ m = 8, which is an even number.

Hence,

➻ No. of images (n) = m - 1

➻ No. of images (n) = 8 - 1

➻ No. of images (n) = 7

$\Large\bf{Therefore,}$

(b) Number of images formed are 7.

_____________________

❷

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{\theta}\:=\:m}$

Where,

θ = 60°

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{60^{\circ}}}$

$:\longrightarrow\:\:\bf{6}$

Thus,

➻ m = 6, which is an even number.

Hence,

➻ No. of images (n) = m - 1

➻ No. of images (n) = 6 - 1

➻ No. of images (n) = 5

$\Large\bf{Therefore,}$

(a) Number of images formed are 5.

_____________________

❸

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{\theta}\:=\:m}$

Where,

θ = 120°

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{120^{\circ}}}$

$:\longrightarrow\:\:\bf{3}$

Thus,

➻ m = 3, which is an odd number.

Hence,

➻ No. of images (n) = m

➻ No. of images (n) = 3

$\Large\bf{Therefore,}$

(b) Number of images formed are 3.

_____________________

❹

θ = 90°

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{\theta}\:=\:m}$

Where,

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{90^{\circ}}}$

$:\longrightarrow\:\:\bf{4}$

Thus,

➻ m = 4, which is an even number.

Hence,

➻ No. of images (n) = m - 1

➻ No. of images (n) = 4 - 1

➻ No. of images (n) = 3

$\Large\bf{Therefore,}$

(a) Number of images formed are 3.

_____________________

❺

↝ All the mirrored walls are perpendicular to each other, i.e

θ = 90°

★ Considering two adjacent walls.

$:\longrightarrow\:\:\bf{\dfrac{360^{\circ}}{90^{\circ}}}$

$:\longrightarrow\:\:\bf{4}$

Thus,

➻ m = 4, which is an even number.

Hence,

➻ No. of images (n) = m - 1

➻ No. of images (n) = 4 - 1

➻ No. of images (n) = 3

↝ These images formed by the combination of two adjacent walls will be in addition to the object itself act objects for the floor mirror (totally 4), thus the total number of images formed will be,

➻ No. of images (n') = 3 + 4

➻ No. of images (n') = 7

$\Large\bf{Therefore,}$

Number of images formed are 7.

_____________________

❻

Given,

Velocity of a man towards a stationary mirror is 5 m/s.

✯ Speed of image :

➣ Speed of object = Speed of image

➣ Speed of image = 5 m/s

Since,

↝ The direction of movement is opposite, thus

➣ Speed of image = - 5 m/s

$\Large\bf{Therefore,}$

(c) The velocity of the image w.r.t ground is - 5 m/s.

_____________________

❼

Given,

Speed of a man away from a stationary mirror is - 10 m/s (negative direction).

✯ Speed of image :

➣ Speed of object = Speed of image

➣ Speed of image = - 10 m/s

Since,

↝ The direction of movement is opposite, thus

➣ Speed of image = - (- 10) m/s

➣ Speed of image = 10 m/s

✯ Image approaching the running man with same speed. Hence relative velocity of image w.r.t running man is

➣ Relative velocity of image = 10 - (-10)

➣ Relative velocity of image = 20 m/s

$\Large\bf{Therefore,}$

The velocity of the image w.r.t man is 20 m/s.

_____________________

❽

Given,

Speed of a mirror towards a stationary man is 5 m/s.

↝ The speed of the image will be twice that of the object i.e. 10 m/s.

➣ This is due to the fact that when you bring the mirror closer to the object, the image also moves closer.

➣ Thus when we move the mirror closer by 5 metres in one second, the image gets closer by 10 metres.

➣ Therefore the image covers twice the distance in same time interval and has its speed equal to twice the object's.

$\Large\bf{Therefore,}$

(b) The speed of the image w.r.t ground is 10 m/s.

_____________________

❾

Given,

Speed of a mirror away from a stationary man is 6 m/s.

➣ When we move the mirror away by 6 metres in one second, the image gets away by 12 metres.

Since,

↝ The mirror is moving away from the man, it's value is opposite.

$\Large\bf{Therefore,}$

(b) The speed of the image w.r.t ground is -12 m/s.

_____________________

❿

Given,

Speed of a man towards a mirror 5 m/s.

Speed of mirror towards the man is 2 m/s.

[NOTE - Man is moving opposite, according to the movement of the mirror, thus Speed of the man is - 5 m/s.]

➻ Speed of image w.r.t mirror = (Speed of object) - (Speed of mirror)

➻ Speed of image w.r.t mirror = (-5) - (2)

➻ Speed of image w.r.t mirror = - 5 - 2

➻ Speed of image w.r.t mirror = - 7 m/s

Thus,

➙ Speed of image w.r.t mirror = (Speed of image w.r.t mirror) - (Speed of mirror)

➙ Speed of image w.r.t mirror = - 7 - 2

➙ Speed of image w.r.t mirror = - 9 m/s

$\Large\bf{Therefore,}$

The speed of image w.r.t ground is - 9 m/s.