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Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

106.

On a particular hot day, the temperature is 40°C and the partial pressure of water vapor in the air is 38.8 mmHg. What is the relative humidity?

 

A.

70

B.

62

C.

80

D.

42

Correct answer is A

Relative Humidity=  partialpressureofH2OsaturatedvaporpressureofH2O×100%

S.v.p. of water at 40°c = 55.3

⇒ Relative Humidity=  38.855.3×100%

Relative Humidity= 70%

107.

A missile is launched with a speed of 75 ms-1 at an angle of 22° above the surface of a warship. Find the horizontal range achieved by the missile. Ignore the effects of air resistance.

[Take g = 10 ms-2]

A.

195 m

B.

271 m

C.

391 m

D.

136 m

Correct answer is C

U= 75 ms1 =22º,   g= 10 ms2 ,   R=?
 

   R=     U2sin2θg


⇒R=     752×sin2(22)10

⇒R=      5625×Sin4410

⇒R=      5625×0.694710

⇒R=      3907.6910


 ⇒    391m

 


108.

Find the tension in the two cords shown in the figure above. Neglect the mass of the cords, and assume that the angle is 38° and the mass m is 220 kg

[Take g = 9.8 ms-2]

A.

T1 = 2864 N, T2= 3612 N

B.

T1= 3612 N, T2 = 2864 N

C.

T1= 3502 N, T2= 2760 N

D.

T1 = 2760 N, T2 = 3502 N

Correct answer is C

W =  mg  = 220 x 9.8 = 2156 N


⇒Sin 38º = 2156T1

T1 =    2156Sin38

T1 =     3502 N

 

Cos 38º =  T2T1

T2  =   3502 x Cos 38º

T2 =   2760 N

 

;    T1 =   3502 N,  T2 = 2760 N.

 

 

109.

Which of the following statements regarding the application of electrical conduction via gases is/are correct?
Electrical conduction in gas is applied in:
(i) The identification of gases
(ii) Lighting/fluorescent tubes
(iii) Photocells
(iv) Cathode ray oscilloscope/T.V. tubes

A.

(i), (iii) and (iv) only

B.

(i), (ii) and (iv) only

C.

(ii), (iii) and (iv) only

D.

(i), (ii) and (iii) only

Correct answer is B

Electrical conduction of gas is applied in:
(i) The identification of gases
(ii) Lighting/fluorescent tubes
(iii) Advertising industry/Neon signs
(iv) Cathode ray oscilloscope/T.V. tubes

110.

The property of wave shown in the diagram above is?

A.

Diffraction

B.

Refraction

C.

Polarisation

D.

Interference

Correct answer is A

Diffraction is the bending of waves around the corners of an obstacle or through an aperture.