projectile (1 Viewer)

[Valupatitta]

A particle is projected with an initial velocity of Vm/s and attains a maximum height of 12.5m before landing 100m from the point of projection. Calculate the value of V.

 

[Timothy.Siu]

A particle is projected with an initial velocity of Vm/s and attains a maximum height of 12.5m before landing 100m from the point of projection. Calculate the value of V.

max is when y'=0
y'=-gt+Vsin@
when y'=0 t=Vsin@/g

y=-0.5gt^2+Vsin@.t
=V^2sin²@/2g=12.5
at max height.
when y=0, x=100

y=0, t(Vsin@+0.5gt)=0
t=-2Vsin@/g
x=Vcos@.t=2V^2sin@cos@/g=100 at that time,
v^2sin2@=100g
and v^2sin²@=25g
dividing,
2cot@=4
cot@=2

subbing back in, v=root(1250)
taking g=10

(did this on computer so might've made mistakes)

 

[cutemouse]

Don't you have to derive all equations for projectiles?

 

[Timothy.Siu]

Don't you have to derive all equations for projectiles?

i did that in my head.
of course u would write them in exams.
i still think i might've done it wrong. used another method and got a different answer llol.