Momentum,
Impulse, Work,
Energy & Power
, Momentum, Impulse, Work, Energy & Power
Linear momentum
Explanation: A physical quantity can be calculated for any moving object of (constant) mass.
Linear motion occurs in 1 dimension, straight line, includes vertical & horizontal
motion. Vector quantity, direction included, same direction as velocity vector.
Definition: The product of the mass and velocity of the object
Equation: p = mv (Linear momentum = mass x velocity) Symbol: p Unit: kg.m.s-1
kg.m.s-1 kg m.s-1 Linear momentum is directly proportional to mass & velocity
Example Example
NB! Make sure the
mass is in kg!
A ball of mass 420g is kicked at A ball of mass 0,05kg moves at a
-1
20m.s calculate the momentum of the velocity of 90.m.s-1 in westerly direction.
ball. Towards to goal is east. Calculate momentum of the ball.
Convert 420g to 0,42kg p = mv
p = mv = (0,05) (90)
-1
= (0,42) (20) = 4,5kg.m.s west
-1
= 8,4kg.m.s towards the goal post/east
Changes in momentum
Explanation: Due to the vector nature of velocity and momentum, an object can experience a
change in momentum if direction or velocity changes. Can occur when object
comes into contact with another object. NB! Always important to
Equation: Δp = pf - pi = (mv)final - (mv)initial Symbol: Δp distinguish which is the
Change in
Initial momentum positive direction.
momentum Final momentum
Example Δp = pf - pi
A 1000kg car initially moved at 16m.s-1 = (1000)(0) - (1000)(16)
east comes to a complete standstill. = -16000
-1
Calculate the change in momentum. Δp = 16000kg.m.s west
Impulse, Work,
Energy & Power
, Momentum, Impulse, Work, Energy & Power
Linear momentum
Explanation: A physical quantity can be calculated for any moving object of (constant) mass.
Linear motion occurs in 1 dimension, straight line, includes vertical & horizontal
motion. Vector quantity, direction included, same direction as velocity vector.
Definition: The product of the mass and velocity of the object
Equation: p = mv (Linear momentum = mass x velocity) Symbol: p Unit: kg.m.s-1
kg.m.s-1 kg m.s-1 Linear momentum is directly proportional to mass & velocity
Example Example
NB! Make sure the
mass is in kg!
A ball of mass 420g is kicked at A ball of mass 0,05kg moves at a
-1
20m.s calculate the momentum of the velocity of 90.m.s-1 in westerly direction.
ball. Towards to goal is east. Calculate momentum of the ball.
Convert 420g to 0,42kg p = mv
p = mv = (0,05) (90)
-1
= (0,42) (20) = 4,5kg.m.s west
-1
= 8,4kg.m.s towards the goal post/east
Changes in momentum
Explanation: Due to the vector nature of velocity and momentum, an object can experience a
change in momentum if direction or velocity changes. Can occur when object
comes into contact with another object. NB! Always important to
Equation: Δp = pf - pi = (mv)final - (mv)initial Symbol: Δp distinguish which is the
Change in
Initial momentum positive direction.
momentum Final momentum
Example Δp = pf - pi
A 1000kg car initially moved at 16m.s-1 = (1000)(0) - (1000)(16)
east comes to a complete standstill. = -16000
-1
Calculate the change in momentum. Δp = 16000kg.m.s west
