3 ms·

> 2) Impulsive Force (mv-mu)/t - This is the reason you pullback the striking fist as quickly as possible. Note that the change in momentum due to the reversing

by yorwba 4y ago

> 2) Impulsive Force (mv-mu)/t - This is the reason you pullback the striking fist as quickly as possible. Note that the change in momentum due to the reversing of direction evaluates the numerator as (mv - (-mu)) = mv+mu along with the denominator t being made as small as possible thus resulting in a larger force. A good example is the game of Billiards/Carrom. This reasoning would suggest that if you put two billiard balls next to each other and pull one of them away, conservation of momentum will result in the other rolling away in the opposite direction at the same speed. I've never seen that happen, and not just because I suck at billiards. When you pull the ball/your fist away, that changes the momentum of your body, not the other ball/your opponent's body that you're now no longer in contact with.

rramadass 4y ago
Your reasoning is wrong. When at rest the momentum of both balls is zero and when you pull one ball away from the other the change in momentum (and hence the force) is opposite to the other ball. Thus there is no collision and transfer of energy i.e. each is independent. It is only at the point of collision that the impulsive force is imparted to the other body. See this Khan Academy video "Impulse and momentum dodgeball example" for detailed understanding: https://www.khanacademy.org/science/physics/linear-momentum/momentum-tutorial/v/impulse-and-momentum-dodgeball-example https://www.khanacademy.org/science/physics/linear-momentum/... Also see article "Momentum Change and Impulse Connection" (note the Rebounding Collison section at the bottom) : https://www.physicsclassroom.com/class/momentum/Lesson-1/Momentum-and-Impulse-Connection https://www.physicsclassroom.com/class/momentum/Lesson-1/Mom...
- yorwba 4y ago
  > when you pull one ball away from the other the change in momentum (and hence the force) is opposite to the other ball. Thus there is no collision and transfer of energy i.e. each is independent Indeed, that was my point. Because "reversing of direction evaluates the numerator as (mv - (-mu)) = mv+mu along with the denominator t being made as small as possible thus resulting in a larger force" is incorrect for the same reason.
  - rramadass 4y ago
    No, you still have not understood it; what i am pointing out is a change in momentum after a collision resulting in the Impulsive Force. See the Khan Academy video i linked for a detailed example with numerical calculations; It walks you through the steps involved. Also from my 2nd linked article; Observe that each of the collisions above involve the rebound of a ball off a wall. Observe that the greater the rebound effect, the greater the acceleration, momentum change, and impulse. A rebound is a special type of collision involving a direction change in addition to a speed change. The result of the direction change is a large velocity change.

by yorwba 4y ago

rramadass 4y ago

Your reasoning is wrong. When at rest the momentum of both balls is zero and when you pull one ball away from the other the change in momentum (and hence the force) is opposite to the other ball. Thus there is no collision and transfer of energy i.e. each is independent. It is only at the point of collision that the impulsive force is imparted to the other body. See this Khan Academy video "Impulse and momentum dodgeball example" for detailed understanding: https://www.khanacademy.org/science/physics/linear-momentum/momentum-tutorial/v/impulse-and-momentum-dodgeball-example https://www.khanacademy.org/science/physics/linear-momentum/... Also see article "Momentum Change and Impulse Connection" (note the Rebounding Collison section at the bottom) : https://www.physicsclassroom.com/class/momentum/Lesson-1/Momentum-and-Impulse-Connection https://www.physicsclassroom.com/class/momentum/Lesson-1/Mom...

yorwba 4y ago
> when you pull one ball away from the other the change in momentum (and hence the force) is opposite to the other ball. Thus there is no collision and transfer of energy i.e. each is independent Indeed, that was my point. Because "reversing of direction evaluates the numerator as (mv - (-mu)) = mv+mu along with the denominator t being made as small as possible thus resulting in a larger force" is incorrect for the same reason.
- rramadass 4y ago
  No, you still have not understood it; what i am pointing out is a change in momentum after a collision resulting in the Impulsive Force. See the Khan Academy video i linked for a detailed example with numerical calculations; It walks you through the steps involved. Also from my 2nd linked article; Observe that each of the collisions above involve the rebound of a ball off a wall. Observe that the greater the rebound effect, the greater the acceleration, momentum change, and impulse. A rebound is a special type of collision involving a direction change in addition to a speed change. The result of the direction change is a large velocity change.