What will be the ratio of total distance moved by a freely falling body till 4 and 5 second of its journey ? (g = 10 m/s2 ).

1 )  What will be the ratio of total distance moved by a freely falling body till 4 and 5 second of its journey ?   (g = 10 m/s² ).

S(4) : S(5)  

A ) 30 : 40  ,                                               B ) 32 : 45 ,

C ) 35 : 45 ,                                               D ) None of these ,

Correct Answer : -  C ) 35 : 45 ,

Solution : -

Formula : -

We have a simple formula for to calculate distance of freely falling object .

S = (g/2)(2t-1)  ,

So total distance covered in 4 seconds : -

S(4) = (10/2){2(4)-1}  ,

S(4) = 5(7) = 35 m .

So total distance covered in 5 seconds : -

S(5) = (10/2){2(5)-1}  ,

S(5) = 5(9) = 45 m  ,

So ,  S(4) : S(5)  = 35 : 45 m   ,  Answer .

 

2 ) A body is falling freely , so what would be the distance covered in only  8^th second ?

A ) 7 m ,                                                     B ) 9 m ,

C ) 10 m ,                                                   D ) None of these ,

Correct Answer : -  C ) 10 m ,     

Solution : -

Formula : -

We have a simple formula for to calculate distance of freely falling object .

S = (g/2)(2t-1)  ,

So first we calculate the total distance covered till 8 seconds : -

S(8) = (10/2){2(8)-1}  ,

S(8) = 5(15) = 75 m .

So total distance covered till 7 seconds : -

S(7) = (10/2){2(7)-1}  ,

S(7) = 5( 13 ) = 65 m .

So now we can calculate the distance covered only in 8^th second : -

S(8) - S(7) = 75 – 65 = 10 m , Answer.

 

3 )  Angle between linear and angular velocity for circular motion : -

A ) 0 degree ,                                                      B ) 45 degree ,

C ) 90 degree ,                                                   D ) 180 degree ,

Correct Answer : -   C ) 90 degree ,

 

4 )  When motor is overloaded , then it draws ………. Current .

A ) very high ,                                                     B ) very low ,

C ) no current ,                                                   D ) None of these ,

Correct Answer : -  A ) very high ,

When motor is overloaded , then it draws huge amount of current which is higher than rated current .

 

5 )  Alternating current ………… measured by DC ammeter .

A ) can be ,                                                         B ) cannot be ,

C ) may or may not ,                                 D ) None of these ,

Correct Answer : -   B ) cannot be ,

 

6 ) The Frequency of AC mains in Pakistan is  ……. ,

A ) 0 hz ,                                                    B ) 50 hz ,

C ) 100 hz ,                                                D ) 180 hz ,

Correct Answer : -  B ) 50 hz ,

The Frequency of AC mains in Pakistan is 50 hz and voltage is between 220 – 240 V .

 

7 )  Ferromagnetic materials are strongly attracted by ……….. ( magnetic field ) .

 

8 ) Zero rest mass means when particle is at rest and its mass is zero .

e.g  Photon has zero rest  mass.

 

8 )  1 gray = 100 radians .

 

10 ) Diamond is a ……… of conductor of electricity .

A ) good conductor ,                       B ) bad conductor ,

C ) may or may not ,                       D ) None of these ,

Correct Answer : -  B ) bad conductor ,

 

11 )  The first operation involved in Carnot cycle is ……….. ,

A ) Adiabatic expansion ,                        B ) Isochoric ,

C ) Isothermal expansion ,                      D ) None of these ,

Correct Answer : -   C ) Isothermal expansion ,

 

12 )  Vectors have maximum ……… (two) components .

 

13) Ballistic missile fails in circumstances of precision due to ………….. ( air resistance ).

 

14 )  A body in motion always changes its …………….. (position vector).

 

15 )  The tides raise the water in the sea roughly a day ………… ( two time ) .

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