Momentum, Impulse, Work , Energy and Power Flashcards
linear momentum
the product of the mass and velocity of the object
vector and is the same direction as the velocity vector
Newton’s second law in terms of momentum
F🔺= 🔺p/ 🔺t
The net force acting on an object is equal to the rate of change of momentum
Isolated system
a system that has no net external force acting on it
internal forces
*
external forces
*
The law of conservation of linear momentum
The total linear momentum of an isolated system remains constant (is conserved)
elastic collision
a collision in which both momentum and kinetic energy are conserved
inelastic collision
a collision in which only momentum is conserved
impulse (J)
J=Fnet🔺t
🔺p = Fnet 🔺t
the product of the net force and the contact time
in the same direction as the net force vector
work done on an object by a force
J
the product of the displacement and the component of the force parallel to the displacement
(scalar)
If energy gained by object, work done on object is positive
If energy lost by object, work done on that object is considered negative
gravitational potential energy
Ep=mgh
the energy an object possessed due to its position relative to a reference point
kinetic energy
Ek=1/2m2
the energy an object has as a result of the object’s motion
mechanical energy
EM=Ep+Ek
the sum of gravitational potential and kinetic energy at a point
The law of conservation of energy
The total energy in a system cannot be created or destroyed; only transformed from one form to another
The principle of conservation of mechanical energy
In the absence of air resistance or any external forces, the mechanical energy of an object is constant
(Ep+Ek)i = (Ep+Ek)f
work-energy theorem
work done by a net force on an object is equal to the change in the kinetic energy of the object
Kinetic energy of a system is increased when Fnet is in the same direction as s
Kinetic energy of a system is decreased when Fnet is in the opposite direction to s
Power
the rate at which work is done
(W)
One watt is defined as the power when one joule of work is done in one second (1W = 1J.s-1)
If force causes an object to move at a constant velocity…
Calculate the power using P = mv
Efficiency
the ratio of output power to input power
%effiency = power out/ power in x 100
