②
V
If
=
formula for
↓ Eu
2V
Vi
=
+
If
·
2V
-
V+
=
Vi
it looking for vi
Velocity
tolook
for
3
a
=
Vf Vi
-
d
t
m/g2
Example :
a
8m/s-3m/s
=
4S
Em
:
1
=
=
1
.
25
.
25.
1 25m/j2
=
.
Derive
A
T
at
at
Vf
#
X&
:
-
Vi
at
=
-
=
+
t
(at
-
Vf- Vi
Vy
=
-
vi)
-
Vf-Vi
Vi
=
it need any V +
Uf
Vi
=
a+ +
Vf
1
Problem solving
A ball is dropped from rest at a height of 50m above the ground
A) With what speed before it hits the ground
B) How long does it take to reach the ground?
Projectile Motion
1.) A body
above the
is
the level ground at an angle of 500
.
initial speed of 40m/s
projected upward from
horizontal . It has
9) How long
Solution
an
will it be before it hits the
:
Vix
ground ?
Vi cos #
=
40 m/s Cros
=
=
50 %
40m/s (0 64)
.
25 60 m/
=
.
Viy
=
=
sin
Vi
40m/s (sin 50%
=
40 M/s (0 77)
=
30 80 m/s
.
.