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What is the definition of the momentum ?
Momentum is a property of moving objects that is calculated by multiplying an object's mass by its velocity
What is the unit of momentum ?
Kgm/s (Kilogram meters per second)
What is the equation for momentum ?
p (momentum) = m (mass) x v (velocity)
What type of quantity is momentum ?
Vector
What is the definition of a ‘scalar quantity’ ?
A quantity that is completely described by its magnitude. It has no direction.
What is the definition of a ‘vector quantity’ ?
A quantity that is completely described by its magnitude and direction
What is the definition of impulse ?
The change in momentum of an object
How is force linked to momentum ? (What is the equation ?)
F (force) = m (mass) x v (final velocity) - u (initial velocity) / t (time)
“ Force is equal to the mass times the change in velocity over time”
What Is the 2 equations for impulse ?
p (change in momentum) = p (final) - p (initial) = m ( v - u )
p (change in momentum) = F(force) x t(time)
What type of quantity it impulse ?
Vector quantity
What is the unit for impulse ?
Ns (Newton second)
If a ball is hit by a racket which exerts a force of 200N on the ball , then what force does the ball exert on the racket ? (NB : justify using newtons 3rd law)
According to newtons 3rd law , every action has an equal and opposite reaction. Therefore the force exerted by the ball onto the racket is equal to the force exerted by the racket onto the ball in the opposite direction. Therefore the force exerted by the ball on the racket is 200N in the opposite direction.
What is the definition of inertia ?
The unwillingness of an object to move
What is the principle of conservation of momentum?
“ The total momentum before an explosion/collision is equal to the total momentum after an explosion/collision in a closed system ”
(For an example where a cannon ball is shot out of a cannon) taking momentum to the right to be positive and the momentum to the left as negative ; comment on the moment if the cannon and ball before , during and after the firing ?
The total momentum of the cannon ball before , during and after the firing is 0. This is because of the principle of conservation of momentum ; it sates that the total momentum does not change. Therefore if the ball has positive momentum, then the cannon has the negative momentum of the same magnitude.
A fielder , as he catches a cricket ball , pulls his hand backwards. Explain why this action reduced the force on his hands ? (3 marks)
It increase the time it takes for the cricket ball to come to a stop for the same change in momentum as the ball goes from (insert initial velocity) to (insert final velocity) , this reduced the average force on the cricketer’s hand.