1 ) A force of 50 N is acted on a body of mass 5 kg which is at rest , for an interval of 3 secs , then impulse is : - A ) 100 N / sec , B ) 120 N / sec , C ) 150 N / sec , D ) None of these ,

1 )  A force of 50 N is acted on a body of mass 5 kg which is at rest , for an interval of 3 secs , then impulse is : -

A ) 100  N / sec ,                                                                  B ) 120  N / sec ,

C ) 150  N / sec ,                                                                  D ) None of these ,

Correct Answer : -  

Solution : -

I = f x t ,

I = 50 x 3 = 150  N / sec .

 

2 ) The resultant of two forces can be zero , when they have : -

A ) same magnitude and opposite direction .

B ) same magnitude and same direction .

C ) opposite magnitude and same direction .

D ) opposite magnitude and opposite direction .

Correct option : -  A ) same magnitude and opposite direction .

 

3 ) The maximum and minimum magnitudes of resultant of given vectors are 17 units and 7 units . If these two vectors are at right angles to each other , then magnitude of their resultant is : -

A ) 5 ,                                                              B ) 13 ,

C ) 44 ,                                                                       D ) None of these ,

Correct Answer : -   B ) 13 ,

Solution : -

Let two vectors  a  and  b .

According to question  : -

a + b = 17     and      a – b = 7 .

So ,   a = 12   and   b = 5  .

So ,  R  =  √ ( a ^ 2  +  b ^ 2 )

R  =  √ ( 144 + 25 )  =   13   ,  Answer .

OR

4 ) Two forces  P and Q  have a resultant perpendicular to  P . The angle between the force is : -

Solution : -