Few Mechanics Questions

[S.M.A.T]

I LOVE YOU lol


just one doubt

why did we use -0.5 and 3.5

why not use 0.5 as positive and keep 3.5 as 4

will we get the same answer?

When we use motion formula like s=ut+0.5at^2,v^2=u^2+2as etc ,the 's' represent resultant displacement, for example a ball is is thrown at an angle from a cliff which 5m from ground level so resultant vertical displacement is -5m

The negative sign indicates that the ball moved extra 0.5m downward i.e resultant vertical displacement is 0.5m downward shown in diagram 1
U can not keep 3.5 as 4 because when the ball moved horizontally 10m, the ball has a resultant vertical displacement of 3.5 shown in diagram 2

If u still have problem then ask me

[yasser37]

Thanks a lot m8

really helped me there

+rep

[cooldude]

for the third part solve the equation
tan 20=[30+(12t-5(t^2))]/16t
lets consider A as the origin, angle RAB basically means the angle that R's horizontal and vertical displacements make wrt A. so R's horizontal displacement is 16t and its vertical displacement wrt A is 30+12t-5(t^2), see the diagram attached to get a clearer idea of the explanation, p.s. sorry about the bad handwriting

in the diagram RAB is A, and y and x are the vertical and horizontal displacements respectively.