Using initial condition
Sol. 1 a = Kt − 2 x
at t = 0
d 2x
2
=a x = 0, x&= 0,
dt
d 2x Calculating the value of A and B
2
= Kt − 2
x
dt A=0
On solving the differential equation −K
B= 3
x = C.F . + P.I . Kt K sin( t )
x= −
C.F . = A cos( t ) + B sin( t ) 2
3
Kt
P.I . =
2
Kt
x = A cos( t ) + B sin( t ) +
2
Sol.2 v = u + at
0 = v0 cos( ) − gt
v0 cos( )
t=
g
2v0 cos( )
Total time of flight= 2t =
g y
Horizontal distance travelled by ball
1
s = ut + at 2 x
2
2
2v0 cos( ) 1 2v0 cos( )
s = v0 sin( ) − 0.4
g 2 g
s=0 ball return back to boy hand
0.2 4
tan( ) =
2 g
= 2.33490
Sol.3 a = an eˆn + at eˆt
v2 eˆt
a= eˆn + v&eˆt
eˆn
For weightlessness 𝑎𝑛 = 𝑔
v2
9.79 =
= 5044.1987 m
v
=
&
&= 2.5241deg/ s