Conservation Laws Flashcards
What is energy?
The ability to do work. Measured in joules.
Alternatively, it is the ability to apply a force for a given displacement.
What is work?
The measure of the amount of energy transferred when a force acts on an object for a given displacement.
The product of the magnitude of applied force and displacement of the object in the direction of the force.
If you push down on a box, and it is moving to the side, how much work have you done?
None.
1 Joule. What are the equivalent units?
N * m
or
kg * m^2 / s^2
Efficiency equation.
(Wout / Win) * 100%
For example, if you put in 100J, but only 50J of work was done, you were 50% efficient.
What is power?
The rate at which work is done. Measured in Watts.
1 Watt. Equivalent units.
J/s
or
Nm/s
or
kg m^2 / s^3
What is kinetic energy?
The energy of motion itself. The energy possessed because of motion.
Ek=1/2 m v^2
What is momentum?
How difficult it is to stop an object. A vector quantity with units of kg m/s.
Is momentum conserved in a collision?
Yes, always.
How is momentum changed?
A net force is needed to change a body’s momentum.
What is an impulse?
A force acting on an object for a time. Units are Ns
An impulse is equal to a change in momentum.
What is the difference between elastic and inelastic collisions?
In elastic collisions, kinetic energy is conserved. Eki=Ekf
In inelastic collisions, kinetic energy is not conserved.
Note that momentum is always conserved.
What are the different kinds of potential energy?
Chemical: gasoline, batteries, etc.
Electric potential: Voltage.
Elastic potential: Springs.
Gravitational potential: Work done by or against gravity.
What is Hooke’s law?
Stretch produced by a force applied to a spring was proportional to the magnitude of the force.
F=kx where k is the elastic/spring constant (this changes depending on the spring).
