1. The temperature at which the speed of sound becomes double as was at 27°C is

1. 1. 273° C

   
   
   

   2. 0° C

   
   
   

   3. 927° C

   
   
   

   4. 1027°C

   
   
   

---

1. View Hint View Answer Discuss in Forum

   We have c ∝ √T
   

   ∴	c1	= √	T1
   	c2		T2

   
   

   ⇒	c1	= √	(27 + 273)k
   	2c2		T2

   
   ⇒ T₂ = 1200k = 927°C

   Correct Option: C

   We have c ∝ √T
   

   ∴	c1	= √	T1
   	c2		T2

   
   

   ⇒	c1	= √	(27 + 273)k
   	2c2		T2

   
   ⇒ T₂ = 1200k = 927°C

---

2. Which of the following equations represent a wave?

1. 1. y = A sin ωt

   
   
   

   2. y = Acos kx

   
   
   

   3. y = A sin (at – bx + c)

   
   
   

   4. y = A (ωt – kx)

   
   
   

---

1. View Hint View Answer Discuss in Forum

   y = A sin (at – bx + c) represents a wave, where a may correspond to ω and b may correspond to K.

   Correct Option: C

   y = A sin (at – bx + c) represents a wave, where a may correspond to ω and b may correspond to K.

---

---

3. A wave of frequency 100 Hz is sent along a string towards a fixed end. When this wave travels back after reflection, a node is formed at a distance of 10 cm from the fixed end of the string. The speeds of incident (and reflected) waves are

1. 1. 5 m/s

   
   
   

   2. 10 m/s

   
   
   

   3. 20 m/s

   
   
   

   4. 40 m/s

   
   
   

---

1. View Hint View Answer Discuss in Forum

   As fixed end is a node, therefore, distance between two consecutive nodes
   

   -	λ	- 10 cm.
   	2

   
   λ = 20 cm = 0.2 m
   As v - nλ ∴ v = 100 × 0.2 = 20 m/s

   Correct Option: C

   As fixed end is a node, therefore, distance between two consecutive nodes
   

   -	λ	- 10 cm.
   	2

   
   λ = 20 cm = 0.2 m
   As v - nλ ∴ v = 100 × 0.2 = 20 m/s

---

4. A standing wave is represented by y = Asin (100t) cos (0.01x), where y and A are in millimetre, t in seconds and x is in metre. Velocity of wave is

1. 1. 10⁴ m/s

   
   
   

   2. 1 m/s

   
   
   

   3. 10^-4 m/s

   
   
   

   4. not derivable from above data

   
   
   

---

1. View Hint View Answer Discuss in Forum

   The wave equation is y = Asin (ωt)cos (kx);
   c = ω/k = 100/0.01 = 10⁴ m/s.

   Correct Option: A

   The wave equation is y = Asin (ωt)cos (kx);
   c = ω/k = 100/0.01 = 10⁴ m/s.

---

---

5. With the propagation of a longitudinal wave through a material medium, the quantities  transmitted in the propagation direction are

1. 1. Energy, momentum and mass

   
   
   

   2. Energy

   
   
   

   3. Energy and mass

   
   
   

   4. Energy and linear momentum

   
   
   

---

1. View Hint View Answer Discuss in Forum

   With the propagation of a longitudinal wave, energy alone is propagated.

   Correct Option: B

   With the propagation of a longitudinal wave, energy alone is propagated.

---