Question

the air causes a verticle retardation equal to 10% of the acceleration due to
gravity (Take g = 10 ms-2). The maximum height will be decreased by:-
(4) 11%
(1) 8%
(3) 10%
(2) 9%​

Answer 1

Answer:we know,

h= ut + (1/2)gt^2

= ut+ (1/2)*10*t^2

= ut+ 5t^2.......(1)

Now vertical retardation due to air is 10% of g.

That is , g'= 10% of 10= 1m/s^2

Now , in presence of retardation due to air,

h'= ut+(1/2)(g-g')t^2

= ut+(1/2)(10-1)t^2

= it+( 4.5)t^2........(2)

Now, decrease in height is given by

H= (h-h')

= (ut+5t^2)-(ut+4.5t^2)

= 0.5t^2

Now percentage decrease in height will be given by

(0.5t^2/5t^2)*100%

=(50/5)%=10%