Unit Conversion, Speed,
and Acceleration
• Write down what units you are given
• Mile
• Write down what units you need to change to (at the end)
• Inches
• Determine conversions that you need to make,
• Mile -> yard-> feet -> inches
• Make sure you place the correct units on the top/bottom of the
conversion.
1 mile x 5280 yards x 3 feet x 12 inches
mile
yard
foot
Unit Conversion
(Changing from one unit to another)
• Write down what units you are given
• Mile
• Write down what units you need to change to (at the end)
• cm
• Determine conversions that you need to make,
• Mile -> meters -> centimeters
• Make sure you place the correct units on the top/bottom of the
conversion.
1 mile x 1609 meters x 100 cm
mile
meter
Unit Conversion
(Changing from one unit to another)
• You do this one….
Unit Conversion
(Changing from one unit to another)
∆𝒅
• Savg =
∆𝒕
• S
∆
• d
• t
=
=
=
=
Speed
Change in
distance
time
Average Speed
d
s
t
• A runner finished a 10 km run in 32 minutes, what was
his speed?
• That same runner continued to run at his 10 km speed
(.31 km/min)for another 15 minutes, how far did he run in
these next 15 minutes? How far was his total run?
• The same runner liked running so much he continued to
run for another 8 km at the same speed (.31 km/min),
how much time did it take from start to finish?
With your table partner…
A runner finished a 10 km run in 32 minutes, what was his
speed?
Speed = d/t = 10 km / 32 min. = .31 km / min.
Speed?
That same runner continued to run at his 10 km speed
(.31 km/min)for another 15 minutes, how far did he run in
these next 15 minutes? How far was his total run?
Distance = s x t = .31 km / min. x 15 = 4.65 km
10 km + 4.65 km = 14.65 km
Distance
The same runner liked running so much he continued to run
for another 8 km at the same speed (.31 km/min), how
much time did it take from start to finish?
Time = d/s = 8 km/.31 km/min = 25.8 minutes
32 min. + 15 min. + 25.8 min. = 72.8 minutes
(1:12:48)
Time
• Vavg=
∆𝑑
∆𝑡
• V=Velocity
∆= Change in
• D=displacement
• T=time
Average Velocity
• If a baby monkey rides backwards on a pig for 1 meter in
2 seconds, what is it’s velocity?
What do I know
d = 1 meter
t = 2 seconds
∆𝑑
Vavg=
∆𝑡
Term/variable to
solve for
V=Velocity
Formula to use
Vavg=
1 meter
𝟐 𝒔𝒆𝒄𝒐𝒏𝒅𝒔
Vavg = .5 meters
second
BACKWARDS
Sample Problem
• If a baby monkey rides backwards on a pig for 1 meter in
2 seconds, what is it’s velocity?
What do I know
d = 1 meter
t = 2 seconds
∆𝑑
Vavg=
∆𝑡
Sample Problem
Term/variable to
solve for
V=Velocity
Formula to use
Vavg=
∆𝒅
∆𝒕
Mechanics in Football
Calculating
Acceleration
• Acceleration is a change in velocity (∆V)
• Velocity is a vector so it includes
direction
• A change in velocity might be a change in
direction with out changing speed or it
could be a change in speed
What is acceleration?
a – acceleration
• a = vf – v i
Vf – Final Velocity
(How fast an object travels
at the end)
___________________
t
Vi – Initial Velocity
(How fast an object starts
out traveling)
t - Time
How do I find acceleration?
• Mr. Moyer shoots a dart from his dart gun
at a student. The dart travels at 5 m/s for .5
seconds until it misses the student’s dome
and hits the wall. Assuming the dart starts
at rest in the dart gun, what is the
acceleration of the dart?
Sample Problem
• Mr. Moyer shoots a dart from his dart gun at a
student. The dart travels at 5 m/s for .5
seconds until it hits the wall. Assuming the dart
start at rest in the dart gun, what is the
acceleration of the dart?
What do I know
Vi = 0 m/s
Vf = 5m/s
T = .5 s
Sample Problem
Term/variable to
solve for
Acceleration (a)
Formula to use
a = Vf –Vi
t
• Mr. Moyer shoots a dart from his dart gun
at a student. The dart travels at 5 m/s for .5
seconds until it hits the wall. Assuming the
dart start at rest in the dart gun, what is the
acceleration of the dart?
What do I know
Vi = 0 m/s
Vf = 5m/s
T = .5 s
Term/variable to
solve for
Acceleration (a)
Formula to use
a = 5m/s – 0m/s
.5 s
a = 10 m
s2
Sample Problem
• If a toy car accelerates at 10 m/s2 and
the car started at rest, how fast was the
car going at the end of 15 seconds?
What do I know
Vi = 0 m/s
t = .5 s
a=3m
s2
Sample Problem
Term/variable to
solve for
Formula to use
Vf = ?
Now manipulate formula
to get Vf by itself
a = Vf –Vi
t
(a x t) + Vi = Vf
• If a toy car accelerates at 10 m/s2 and
the car started at rest, how fast was the
car going at the end of 15 seconds?
What do I know
Vi = 0 m/s
t = .5 s
a = 10 m
s2
Sample Problem
Term/variable to
solve for
Formula to use
(a x t) + Vi = Vf
Vf = ?
(10m/s x .5s) + 0 m/s = Vf
5 m = Vf
s
• A car starts out driving 25 m/s then
accelerates to 50 m/s in 30 sec. What
is the acceleration of the car?
What do I know
Vi = 25 m/s
Vf = 50 m/s
T = 30 s
Sample Problem
Term/variable to
solve for
Acceleration (a)
Formula to use
a = Vf –Vi
t
• A car starts out driving 25 m/s then
accelerates to 50 m/s in 30 sec. What
is the acceleration of the car?
What do you know
Vf =
Vi =
t =
a =
What formula are you going to use????
Now you try…
a = vf – v i
t
• A car starts out driving 25 m/s then
accelerates to 50 m/s in 30 sec. What
is the acceleration of the car?
What do you know
Vf =50 m/s
Vi =25 m/s
t = 30 s
a =
formula to use
a = vf – vi
t
Plug in your numbers…
a = 50 m/s – 25 m/s
30 s
Now you try…
• A car starts out driving 25 m/s then
accelerates to 50 m/s in 30 sec. What
is the acceleration of the car?
Plug in your numbers…
a = 50 m/s – 25 m/s
30 s
a = 25 m/s
30 s
a = .83 m/s/s => .83 m/s2