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)