Post on 23-Jun-2015
description
transcript
Projectile motion
Graphs
A
A
B
B
CC
D
D
A
B
C
D
Questions: A-B
From A to B:a) Calculate the object’s displacement.b) Calculate the object’s acceleration.
A
B
Time (s)
Velo
city
(m•s
-1)
Displacement A-B
The area under a v-t graph gives the object’s displacement during that time period.AreaA-B = ½ base x height
= ½ (1 s x 10 m•s-1)= 5 m= 5 m upward
B
Time (s)
Posi
tion
(m)
A
A
B
Time (s)
Velo
city
(m•s
-1)
Acceleration A-B
GradientA-B =
= === - 10 m•s-2
= 10 m•s-2 downward
Questions: B-C
From B to C:a) Calculate the object’s displacement.b) Calculate the object’s acceleration.
Time (s)
Velo
city
(m•s
-1)
C
B
Displacement B-C
The area under a v-t graph gives the object’s displacement during that time period.AreaB-C = ½ base x height
= ½ (2-1)s x (-10-0) m•s-1
= ½ (1s x -10 m•s-1)= -5 m= 5 m downward
Time (s)
Posi
tion
(m)
C
B
Questions: A-C
From A to C:a) Calculate the object’s displacement.b) Draw an acceleration-time graph for the motion.
Time (s)
Velo
city
(m•s
-1)
C
A
B+5m
-5m
Displacement A-C
The combined areas under the A-B and B-C lines for the v-t graph gives the displacement for interval A-C.AreaA-C = AreaA-B + AreaB-C
= 5 m – 5 m= 0 m
Time (s)
Posi
tion
(m)
C
B
A
Time (s)
Velo
city
(m•s
-1)
C
B
A
Acceleration A-C
0 0.5 1 1.5 2 2.5
-12-10
-8-6-4-20
Time (s)
Acce
lera
tion
(m•s
-2)
A
B
Time (s)
Velo
city
(m•s
-1)
A
B
CD
Time (s)
Posi
tion
(m)