Projectiles

1
Projectiles
Launched at an
Angle
2
Review
A Honda Civic with a whale tail, racing stripes,
neon lights on the undercarriage, and a 5000 Watt
stereo is driven off a cliff at 25 m/s and lands
60m from the base of the cliff. How high is the
cliff?
Vertical
Horizontal
vH 25 m/s
dH 60 m
t d / v
60 / 25
2.4 s
v0 0 m/s
a -9.8 m/s2
t 2.4 s
d v0t ½at2
0 ½(9.8)(2.4)2
-28 m (distance car fell)
The cliff is 28 m high
3
Projectiles launched at an angle

• A soccer ball is kicked from ground level with an
  initial velocity of 25 m/s at an angle of 37
  from horizontal.
• Find the horizontal and vertical components of
  the initial velocity.

vH 25 x cos37
20 m/s
25m/s
vV
vV 25 x sin37
15 m/s
37
vH

• Find the time of the flight.
• Find the distance the ball goes (range).
• Find the velocity 1.0 second after the kick.

4
Vertical
Horizontal
v0 15 m/s
a -9.8 m/s2
b)
d 0 m
t ?
d v0t ½at2
0 15t 4.9t2
0 15 4.9t
t 3.1 s
d v x t
c)
62 m
20 x 3.1
vV v0 at
d)
vH 20 m/s
d)
15 (-9.8)(1.0)
20 m/s
5.2 m/s
5.2 m/s
Velocity _at_ 1.0 s 20.67 m/s, 14.6 above
horizontal (75.4 from vertical)
5
Assignment

• Homework
• Textbook Page 113
• Questions 22, 23, 25, 29, 30

6

• A baseball is hit with an initial velocity of 200
  m/s at an angle of 30 with horizontal. Find
• the time of the flight.
• The maximum height of the mortar shell.
• The range of the mortar shell.
• The velocity of the mortar shell after 15 seconds.