2. Why is it a bad idea to
bungee jump with a
chain?
3. 3.2: LEARNING TARGET 3
What will I be able to The student can describe impulse as a change in
do when I’ve finished momentum
this lesson?
What idea, topic, or
subject is important
for me to learn and
understand so that I
can do this?
To be able to do this, I must learn and understand…
• What impulse is
• How impulse is measured
• How impulse is calculated
What will I do to
show that I can do
this, and how well
will I have to do it?
I will show my understanding of impulse by…
• Identifying the units used to measure impulse
• Identifying the equations used to calculate impulse
• Creating a scenario showing 1) an object gaining
momentum, and 2) an object losing momentum
4. IMPULSE
A change in momentum!
How can we change momentum?
What would the equation for changing momentum look like?
6. IMPULSE = CHANGE IN MOMENTUM
What units would this equation give us?
Describe an object that has gained momentum
Describe an object that has lost momentum
7. 3.2: LEARNING TARGET 3
What will I be able to The student can describe impulse as a change in
do when I’ve finished momentum
this lesson?
What idea, topic, or
subject is important
for me to learn and
understand so that I
can do this?
To be able to do this, I must learn and understand…
• What impulse is
• How impulse is measured
• How impulse is calculated
What will I do to
show that I can do
this, and how well
will I have to do it?
I will show my understanding of impulse by…
• Identifying the units used to measure impulse
• Identifying the equations used to calculate impulse
• Creating a scenario showing 1) an object gaining
momentum, and 2) an object losing momentum
8. 3.2: LEARNING TARGET 3
I will show my understanding of
What will I impulse by…
do to show • Identifying the units used to
measure impulse
that I can
• Identifying the equations used
do this, and
to calculate impulse
how well
• Creating a scenario showing
will I have
1) an object gaining
to do it?
momentum, and
2) an object losing momentum
10. 3.2: LEARNING TARGET 4
What will I be able to
The student can describe impulse as a result of force and
do when I’ve finished
time
this lesson?
What idea, topic, or
subject is important
for me to learn and
understand so that I
can do this?
To be able to do this, I must learn and understand…
• What impulse is
• How impulse is related to acceleration, and thus force
• How to calculate impulse in a variety of ways (using a
change in momentum, and force and time)
What will I do to
show that I can do
this, and how well
will I have to do it?
I will show my understanding of impulse by…
• Calculating impulse as it is related to force and time
• Creating a scenario showing 1) an object losing
momentum quickly, and 2) an object losing momentum
slowly
• Create a devise out of household objects to keep an
egg from breaking when dropped from the second
floor
11. IMPULSE AND FORCE!
What is an impulse?
What variables can change momentum?
Which of these two variables is most likely to change?
If velocity changes, what must the object be doing?
What causes acceleration?
Since an impulse is a change in momentum, and velocity is
likely to change, and acceleration has to be present, which
means a force must be applied, then impulse can also be
calculated in terms of force!
13. I = FT
Stopping requires the same impulse (change in momentum)
14. I=
F
T
Stopping requires the same impulse (change in momentum)
Stopping quickly (slamming into a brick wall) results in a
small time, and large force… OUCH!!!
15. I=
T
F
Stopping requires the same impulse (change in momentum)
Stopping quickly (slamming into a brick wall) results in a
small time, and large force… OUCH!!!
Stopping slowly (slamming into a pile of hay) results in a
large stopping time and small force… WHEW!!!
16. Devise a way to
keep an egg from
breaking using
household items.
•
Draw a sketch of
your contraption.
•
Be sure you use
things you actually
have at your house.
17. PROBLEM:
A golfer swings their club with a force of 2000 N and makes
contact with the ball for 0.5 seconds.
a)
How much force does the ball exert back on the club?
b)
How much impulse does the ball experience?
18. PROBLEM:
A baseball player hits a ball and makes contact for 0.25 s,
giving an impulse of 875 N•s, how much force did he exert on
the ball?
19. PROBLEM:
If a softball player exerts an impact force of 1500 N for 0.25
seconds when she strikes the ball, what is the impulse, or
change in momentum, of the ball?
What if she follows through and makes contact for 0.5
seconds?
20. PROBLEM:
A 2200 kg SUV traveling at 94 km/h (26 m/s) can be stopped
in 21 seconds by gently applying the brakes, in 5.5 seconds
in a panic stop, or in 0.22 seconds if it hits a concrete wall.
What average force is exerted on the SUV in each of these
stops?
a.
in 21 s…
b.
in 5.5 s…
c.
in 0.22 s…
21. PROBLEM:
A car moving at 10 m/s crashes into a barrier and stops in 0.050 s.
There is a 20 kg child in the car. Assume that the child’s velocity is
changed by the same amount as the car’s in the same time period.
a. What impulse is needed to stop the child?
b. What is the average force on the child?
c. What is the approximate mass of an object whose weight
equals the force in part b.
d. Could you lift such a weight with your arms?
e. Why is it advisable to use a proper infant restraint rather that
hold a child on your lap?
22. PROBLEM:
Small rockets are used to make tiny adjustments in the speed of
satellites. One such rocket has a thrust of 35 N. If it is fired to
change the velocity of a 72,000 kg spacecraft by 63 cm/s, how long
should it be fired?
