Physics (Essay) Paper 2 May/June 2015

Question 2

A body is projected at an angle of 30o to the horizontal with a velocity of 150ms-1
Calculate the time it takes to reach the greatest height.
                                    [ Take g = 10 ms-2  and neglect air resistance]
           

Observation

The question on projectile numerical was popular among the candidates and it was fairly attempted.  Some candidates could not differentiate total time of flight ‘T’ from the time taken to reach the maximum height ‘t’.  The time t was needed to solve the question.  Few candidates omitted correct unit of time while others wrote wrong units.

The expected answer is

 

 

    
vy  =  usinθ - gt                                     
0   =  150 sin 30  -10t   

            t  =  7.5 s                     

 

                                                                    OR
2.          t  =                    
                 =                 
                 =       7.5 s