a body is projected at an angle 30 degree with the horizontal so that it's time of flight is 10 second . Find the speed of the projection of body.
Answer (1)
1st Nov, 2019
Explanation:
(b)
The horizontal component of velocity is constant so we can write:
d
=
v
x
t
d
=
v
cos
θ
t
d
=
40
×
cos
30
×
5
=
173
x
m
(a)
I'll set the point of launch to be the origin and use the convention that "up is +ve".
We can use:
s
=
u
t
+
1
2
a
t
2
This becomes:
h
=
v
y
t
−
1
2
g
t
2
h
=
v
sin
θ
t
−
1
2
g
t
2
h
=
40
sin
30
×
5
−
1
2
×
9.81
×
5
2
x
m
h
=
100
−
122.625
=
−
22.625
x
m
This means that the top of the tower is 23 m above the ground.
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