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Momentum. Momentum and Sports "Going into the all-star break, the Chicago White Sox have the momentum.""Going into the all-star break, the Chicago White.

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Presentation on theme: "Momentum. Momentum and Sports "Going into the all-star break, the Chicago White Sox have the momentum.""Going into the all-star break, the Chicago White."— Presentation transcript:

1 Momentum

2 Momentum and Sports "Going into the all-star break, the Chicago White Sox have the momentum.""Going into the all-star break, the Chicago White Sox have the momentum." "Chicago Bears Gaining Momentum.""Chicago Bears Gaining Momentum." "You have the momentum; the critical need is that you use that momentum and bury them in this third quarter." – A quote from a coach trying to pump up his team!!"You have the momentum; the critical need is that you use that momentum and bury them in this third quarter." – A quote from a coach trying to pump up his team!! What do all these phrases have in common?What do all these phrases have in common? –MOMENTUM

3 Momentum is commonly used in sports.Momentum is commonly used in sports. A team that has theA team that has the momentum is on the move and is going to take some effort to stop. Momentum refers to theMomentum refers to the quantity of motion that an object has. –A sports team which is "on the move" has the momentum. –An object in motion ("on the move") then has momentum.

4 What is Momentum? Momentum can be defined asMomentum can be defined as “mass in motion.” “mass in motion.” All objects have mass; so if All objects have mass; so if an object is moving, then it has momentum - it has its MASS IN MOTION. The amount of momentum whichThe amount of momentum which an object has is dependent upon two variables… an object has is dependent upon two variables… –Mass and Velocity In other words, how much stuff is moving and how fast the stuff is movingIn other words, how much stuff is moving and how fast the stuff is moving

5 How can you remember?

6 Equation Momentum = mass * velocityMomentum = mass * velocity p=m*vp=m*v Units??Units?? –kgm/s What is the momentum of a 60-kg halfback moving eastward at 9 m/s?What is the momentum of a 60-kg halfback moving eastward at 9 m/s? –p=m*v –p=(60kg)(9m/s) –p=540kgm/s

7 p=mv The equation illustrates that momentum is directly proportional to an object's mass and to the object's velocity.The equation illustrates that momentum is directly proportional to an object's mass and to the object's velocity. An object has a large momentum if it has a large mass or a large velocity, and both variables are of equal importance in determining the momentum of an object.An object has a large momentum if it has a large mass or a large velocity, and both variables are of equal importance in determining the momentum of an object.

8 EXAMPLE Consider a Mack truck and a roller skate moving down the street at the same speed.Consider a Mack truck and a roller skate moving down the street at the same speed. –Which will have a greater momentum? The considerably greater mass of the Mack truck gives it a considerably greater momentumThe considerably greater mass of the Mack truck gives it a considerably greater momentum Consider that the same Mack truck is at rest, but the roller skate is moving. Consider that the same Mack truck is at rest, but the roller skate is moving. –Which will have a greater momentum? The roller skate.The roller skate. Anything at rest has a momentum of “0”. Anything at rest has a momentum of “0”. It is not an “mass in motion.” It is not an “mass in motion.”

9 Impulse To stop such an object, it is necessary to apply a…To stop such an object, it is necessary to apply a… –Force –AGAINST To stop such an object, it is necessary to apply a force against its motion for a given period of time To stop such an object, it is necessary to apply a force against its motion for a given period of time force

10 The more momentumThe more momentum an object has, the harder an object has, the harder that is to stop It would require aIt would require a greater amount of force or a longer amount of time (or both) to bring an object with more momentum to a halt.

11 This is called an impulseThis is called an impulse –Impulse=change in momentum –or Ft=Δmv

12 ESPN Video Questions 1. Explain why the goal posts have padding around their base.1. Explain why the goal posts have padding around their base. –The padding will increase the time required to stop and decrease the force.

13 2. A 90 kg football player is moving at 7m/s. Calculate the force required to stop him in.4 seconds; in.2 seconds; in.1 seconds.2. A 90 kg football player is moving at 7m/s. Calculate the force required to stop him in.4 seconds; in.2 seconds; in.1 seconds. –Ft=Δmv –F= Δmv/t –F=(90)(7)/(.4) –F=1575N

14 3. Examine the inside of a football helmet. How is the helmet constructed so that the player’s head will have more time to stop during a collision? Why do we want to give the head more time to stop?3. Examine the inside of a football helmet. How is the helmet constructed so that the player’s head will have more time to stop during a collision? Why do we want to give the head more time to stop? –There is space in the interior of the helmet for the head to move, thereby increasing the time.

15 4. List safety features in cars which lengthen the time during a collision in order to decrease the maximum force during that collision.4. List safety features in cars which lengthen the time during a collision in order to decrease the maximum force during that collision.


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