Transcript What is Temperature?

Happy Tuesday!
• Please have out:
o Notebook
o Calculator
o Lab
o Chpt 6 1-10
• Kick-off: What had the biggest effect on
tension in a string?
Momentum
and Impulse
Pair Share
If both are traveling at the
same speed, which is harder
to bring to a stop?
A Volkswagen Bug or a Semi?
Momentum
• Review: What is inertia?
• Momentum is inertia in motion.
• Resistance to change motion.
Example
• Can the Volkswagen Bug
ever have more momentum
than the Semi?
• Momentum = mass X velocity
• A fast small car may have
more momentum than a
large truck diving slowly.
Impulse
• Impulse = change in momentum
• Either mass, velocity, or both
change
• The impulse is dependent on the
amount of force and time.
Impulse
• The greater the impulse
exerted the greater the
change in momentum.
p  F  t
Change in
momentum
Increasing Momentum
• Apply the greatest force for
as long as possible.
• Examples:
• Golfer teeing off
• Baseball player going for a home run
• Both situations require large force and
follow through.
Decreasing Momentum
• Still Force and time
• Example: You are traveling down a SD
highway at 70mph and your brakes stop
functioning. An accident in front of
your mandates that you stop quickly.
• Which do you choose to stop you, the
concrete supports for an overpass or a
strategically placed haystack?
Decreasing Momentum
t or Ft
• F
• Both will decrease momentum.
Extend the time in which momentum is
brought to zero.
Airbags same idea.
Pair Share Bungee
Jumping
• Do you really need a specific
cord? Wouldn’t a rope work just
as well?
• The cord has to apply an impulse
equal to the jumpers momentum
in order to stop the jumper.
• Bungee impulse = F
• Rope impulse =
Ft
t
Sample Problem
• The hockey player, who has a mass of 89.0
kilograms, is flying at 7.5 m/s above the ice when he
suddenly slams into the ice due to gravity. This
brings his body to a stop in .200 seconds. a) What is
the hockey player’s momentum before he stops?
Sample Problem
• b) What average force is exerted by the ice to stop
his body?
Sample Problem
• c) If he had been a lacrosse player, landing on a
softer turf surface, the time in which he came to a
stop might have been .56s. What average force
would have been exerted on his body by the turf?
Today
• Please finish Tension Lab
o Hand in when finished.
• Chapter 7 homework #’s 1-5
o Due Thursday