## Model Question Paper Physics Answers

SET-1

##### 1. State Newton’s universal law of gravitation .

**Sol-** It states that Every object in this universe attracts every other objects with a force which is directly proportional to the product of there masses and inversely proportional to the square of distance between them.

##### 2. Write on difference between ‘g’ and ‘G’.

**Sol-**

**Acceleration due to gravity (g)**

a. The acceleration produced in a body freely falling under the gravitational pull of the Earth is known as gravitational due to gravity.

b. The value of ‘g’ is different at different places on the Earth.

c. The value of ‘g’ on the surface of Earth is 9.8m/s2.

**Universal Gravitational Constant (G)**

a. The gravitational force between two bodies of unit masses separated by a unit distance is known as Universal Gravitational Constant.

b. The value of ‘G’ is same at all the places on the Earth.

c. The value of ‘G’ = 6.67*10-11 Nm2/kg2 throughout the universe.

3. Write the types of stress.

sol-

- normal stress
- tangential stress or shearing stress
- hydrolic stress

4. Why rain drops are spherical in shape?

sol- This is due to surface tension and the tendency of water molecules to bind together.

5. What is the difference between isothermal and adiabatic process?

sol-

Parameter |
Isothermal |
Adiabatic |

Definition | It is defined as one of the thermodynamic processes which occur at a constant temperature. | It is defined as one of the thermodynamic processes which occur without any heat transfer between the system and the surrounding |

Heat transfer | It contains the transfer of heat. | It does not contain the transfer of heat. |

Pressure vs volume | The pressure is more in comparison to volume. | The pressure is less in comparison to volume. |

Temperature | The temperature remains constant in such a process. | Temperature changes due to variations in the internal system in such a process. |

Heat | To maintain the temperature, heat can be added or released to the system. | No need to add or release the heat, constant temperature maintenance is not required here. |

Rate of transformation |
The transformation is slow in such a process. |
The transformation is fast in such a process. |

##### 6. Give an example of periodic motion which is not oscillatory

##### sol- Motion of planets around sun.

##### 7. Define transverse wave motion.

##### sol- **Transverse waves cause the medium to move perpendicular to the direction of the wave.** **Longitudinal waves cause the medium to move parallel to the direction of the wave**.

##### 8. a) Write expression for gravitational force acting between two masses m1and m2 separated by

distance ‘r’.

##### sol- *F* = *G*(*m*_{1}*m*_{2})/*R*^{2}

##### b) Write Two Characteristics of Gravitational Force

##### sol- a) It is always attractive in nature.

##### b) it obeys the inverse law

9. a) Draw stress verses strain curve.

b) Mark clearly yield point and breaking point.

sol-

10. Derive an expression for excess pressure inside a liquid drop.

11. a)What is a simple pendulum ?

sol- A simple pendulum can be described as **a device where its point mass is attached to a light inextensible string and suspended from a fixed support**.

b) Write an expression for time period of a simple pendulum.

sol- **T = 2π √R/2g**.

c) What is the effective length of a second pendulum?

sol- The pendulum whose time period is 2 sec is called second pendulum. its effective length is **1 meter**

12. Obtain an expression for work done during an isothermal process.

sol-

13. i) Define the terms :-

a) specific heat capacity

sol- The specific heat capacity is defined as **the quantity of heat (J) absorbed per unit mass (kg) of the material when its temperature increases 1 K (or 1 °C)**, and its units are J/(kg K) or J/(kg °C).

b) Latent heat capacity :-

sol- The latent heat is normally expressed as **the amount of heat (in units of joules or calories) per mole or unit mass of the substance undergoing a change of state**.

ii) Write principle of calorimetry.

sol- The principle of calorimetry (or principle of mixtures) states that **for an insulated system, heat energy lost by the hot body is equal to the heat energy gained by the cold body**. Note: Heat transfer occurs until both the bodies attain the same temperature(t).

14. A transverse harmonic wave on a string is described by

y(x, t) = 3.0 sin (36 t + 0.018 x + π/4)

where x and y are in cm and t in s. The positive direction of x is from left to right.

(a) What is its amplitude?

sol- Amplitude of the given wave, a = 3 cm

(b) What is its frequency?

sol- Frequency of the given wave: f= ω/2π = 36/2×3.14 = 573Hz.

(c) What is the initial phase at the origin?

sol- The equation of progressive wave travelling from right to left is given by the displacement function:

y(x,t)=a sin(ωt+kx+ϕ) … (i)

The given equation is:y(x,t)=3.0 sin (36t+0.018x+4π) …(ii) On comparing equations (i) and (ii), we find that the intial phase angle, ϕ=π/4. 15. Write relation betweena) Frequency and time period.sol- Frequency and time period is **inversely proportional to each other.**b) Wavelength and propagation constant.sol- The propagation constant depends on the optical frequency or wavelength of the light. The frequency dependence of its imaginary part determines the group delay and the chromatic dispersion of the waveguide.c) Wavelength, frequency and wave velocity.sol- Wave velocity = Frequency x wavelengthd) Angular frequency and frequency.sol- A**ngular frequency ω (in radians per second), is larger than frequency ν (in cycles per second, also called Hz), by a factor of 2π.**e) Angular frequency, propagation constant and Wave velocity.sol- **v=kω**16. a)State and prove Bernoulli’s principle.sol-