Ans:- given:
Stress = 9.8 x 10⁷

1= 1.0m

∆I = 0.20 cm = 0.20 x10² m

Q2. (b) At what distance from the gun the bullet will strike the ground, if a bullet is fired with an initial velocity 250 ms -1 at an angle of 30° with the horizontal.

Q3. (a) Suppose we have a vector A and vector C = 12B. How is the direction of vector A x B related to the direction of vector C x A. 

Ans:- If magnitude of B is halved but it remains in the same plane as before then the direction of the vector product C = A x B remains unchanged. Its magnitude may change. 

Q4. (b) What is meant by the resolving power of an optical instrument? Drawing suitable diagrams explain Rayhigh’s Criterion for the limit of resolution of two very close spectral lines. Write formula for the resolving power of (i) Microscope (ii) Telescope

Ans:- Resolving power is described as the opposite of the distance between two objects that can only be settled when viewed by the optical instrument. Two separate pictures should be displayed as separate two separate pictures by optical instruments. The resolving power is calculated as a function of 0= 1.220 x (λD) where 0 is the angular resolution in rradians, λ is wavelength of light and D is the diameter of the optics. 

Resolution means to see two close objects just as separate.

Rayleigh purposed a criterion which can manifest when two closed object can be seen as just as separate. This criterion is known as Lord Rayleigh’s criterion of resolution.According to this criterion two images are said to be just resolved if the position of central maxima of the intensity curves of one coincides with the first minima of the other and vice-versa. This is known as Rayleigh’s criterion of limiting resolution.

Formula for the resolving power of

(i) Microscope

D=λ/2nsine0

Thus, the reciprocal of the limit of resolution gives the resolving power of the microscope.

(R.P)= 2nsin20/λ

(ii) Telescope

0 = 1.22λ/D

Thus, the reciprocal of the limit of resolution gives the resolving power of the telescope.

(R.P) = 1/0 = D/1.22λ

Q5. (a) What you understand by the term Wavelength. Calculate the Frequency and Time Period of a radio wave having its wavelength of 10m propagating in space.

Ans:- Wavelength can be defined as the distance between two successive crests or troughs of a wave. It is measured in the direction of the wave. Wavelength is inversely proportional to frequency. This means the longer the wavelength, lower the frequency.

Q6. (b) Take a small piece of stone and tie it to one end of a string. Hold the other end with your fingers and then try to whirl the stone in a horizontal or vertical circular path. Start with a small speed of rotation and increase it gradually. Observe and Comment –

(i) Do you feel any pull on your fingers when the stone is whirling?

Ans:- Yes feel any pull on your fingers when the stone is whirling, due to tension in the thread which creates centripetal force.

(ii) Observe the path of stone if the string breaks suddenly. Will it continue to move in same circular path or will change the path? Explain your answer with reasons.

Ans:- When a stone is going around a circular path, the instantaneous velocity of stone is acting as tangent to the circle. When the string breaks, then the centripetal force acting on the stone becomes zero. Due to inertia, the stone continues to move along the tangent to circular path. So, the stone flies off tangentially to the circular path