The S.I unit for sound energy is

**A.**Hz**B.**cd**C.**dB**D.**J

**Correct Option: Answer is D**

Every form of energy is measured in joules (J).

**2. **The general definition of elastic modulus is

**A.**\(\frac{stress}{strain}\)**B.**\(\frac{strain}{stress}\)**C.**\(stress \times strain\)**D.**\(\sqrt{\frac{stress}{strain}}\)

**Correct Option: Answer is A**

Elastic modulus is the ratio of pressure (stress) applied to a body to the resistance (strain) produced by the body.

= \(\frac{stress}{strain}\)

**3. **

The diagram above illustrates a simple barometer. Which distance measures the atmospheric pressure?

**A.**PQ**B.**QR**C.**RS**D.**QS

**Correct Option: Answer is B**

The height of the mercury column in a simple barometer is calculated as the atmospheric pressure.

**4. **The property of a body to remain at rest or to continue in uniform motion in a straight line is called

**A.**momentum**B.**Inertia**C.**impulse**D.**Energy

**Correct Option: Answer is B**

**Inertia** is the resistance of any physical object to any change in its velocity. This includes changes to the object’s speed, or direction of motion. An aspect of this property is the tendency of objects to keep moving in a straight line at a constant speed, when no forces act upon them

**5. **During a training session, two footballers pass a ball repeatedly between each other. The ‘to and fro’ motion of the ball is not simple harmonic because the

I. Acceleration of the ball is not directed towards a fixed point

II. Restoring force is not directed towards the centre

III. Acceleration of the ball is not directly proportional to the displacement from a fixed point

Which of the statements above are correct?

**A.**I and III only**B.**I and II only**C.**II and III only**D.**I, II and III

**Correct Option: Answer is A**

In SHM, the body must have acceleration in a direction opposite to the displacement and the acceleration must be directly proportional to displacement. Also, the acceleration must be directed towards its mean position. This is not the case with a football on the pitch.

**6. **A dam is able to hold a large quantity of water because its wall is

**A.**thickest at the top**B.**thickest at the middle**C.**thickest at the bottom**D.**of the same thickness throughout

**Correct Option: Answer is C**

The pressure of the water is much greater deeper down and the dam needs to be thick at the bottom so that it is strong enough to withstand this larger pressure.

**7.**

A body of mass **m **moving around a circle of radius **r **with a uniform speed **v **experiences a centripetal force **F. **The work done by the centripetal force on it is

**A.**Fv**B.**zero**C.**Fmr**D.**Fr / m

**Correct Option: Answer is B**

The work done by centripetal force in the case of a uniform circular motion is 0 joules

**8.**

A block is acted upon by TWO horizontal forces as illustrated in the diagram above. The block accelerates at 1.5ms−². Calculate the mass of the block.

**A.**6kg**B.**9kg**C.**10kg**D.**15kg

**Correct Option: Answer is A**

Total force exerted on the block = (10 – 1)N =9N

Force = mass x acceleration

9 = m x 1.5

m = 9/1.5 = 6kg

**9. **Which of the following quantities are dimensionally independent?

I. Dielectric constant II. Momentum III. Efficiency IV. Refractive index

**A.**I and II**B.**II, III and IV**C.**I, II, III and IV**D.**I, III and IV

**Correct Option: Answer is D**

The quantities Efficiency, Dielectric constant and Refractive index are dimensionless.

**10. **A body is projected with an initial velocity **u** at angle \(\theta\) to the horizontal. If \(R_{max}\) is the maximum range of the projectile, what does the relation \(\frac{u^{2}}{R_{max}}\) represent?

**A.**The vertical distance covered**B.**Acceleration due to gravity**C.**The horizontal distance covered**D.**The acceleration of the body

**Correct Option: Answer is B**

\(R_{max} = \frac{u^{2}}{g}\)

Hence, \(g = \frac{u^{2}}{R_{max}}\)