Energy + Momentum Flashcards
(29 cards)
What is energy?
The ability to do WORK or to alter the surroundings in some way.
Name three examples of energy.
- Kinetic energy
- Gravitational potential energy
- Thermal energy
What does the Law of Conservation of Energy state?
Energy can neither be created nor destroyed. Energy can be transformed from one form to another.
Define work in physics.
Work is done when a force acts on an object and the object undergoes a displacement in the direction of the force.
Is work a scalar or vector quantity?
Work is a SCALAR quantity.
What happens when a force acts opposite to the direction of displacement?
The force does negative work on the object.
What is the formula for total work done on an object?
WT = W1 + W2 + W3 +… OR WT = Fnet•d
What conditions lead to zero work?
- Fapp is present but d=0
- Fapp is perpendicular to d
- Displacement, but Fapp = 0
What is kinetic energy?
The energy due to an object’s translational motion.
What does the Work - Energy Theorem state?
The total work done on an object is equal to the object’s change in kinetic energy.
What is mechanical energy?
Energy an object has due to its motion, position, shape, including kinetic, elastic potential, and gravitational potential energy.
What is gravitational potential energy?
Energy an object has due to its position in the Earth’s gravitational field.
List the three characteristics of gravitational potential energy.
- Eg > 0 when object is raised
- Eg < 0 when object is lowered
- Change in energy is path independent
What is the principle of conservation of total mechanical energy?
Total Mechanical Energy is conserved in cases where an object is moving freely in a gravitational field and frictional forces can be ignored.
What happens to kinetic and potential energy as a car falls?
As the car falls, it loses PE and gains KE.
What does kinetic friction do to an object?
It slows down the motion of an object and transforms kinetic energy into thermal energy.
What is a restoring force in relation to springs?
The spring force is called a Restoring force because it is trying to restore the spring to its relaxed state.
What does Hooke’s Law state?
The amount a force exerted by a spring is directly proportional to the extension of the spring.
Ee
The work done is stored in the spring as Elastic Potential Energy.
Define simple harmonic motion.
A type of periodic motion that occurs when the force on an oscillating body is directly proportional to the displacement from equilibrium.
What factors affect the period of simple harmonic motion?
- As mass increases, the period increases
- As the spring constant increases, the period decreases
What is damped harmonic motion?
In reality, friction and other dissipative forces act to reduce the amplitude of vibration.
Define momentum.
Describes the ‘quantity of motion’ of a moving object; it is the product of an object’s mass and velocity.
What causes a change in momentum?
An object’s momentum changes when it accelerates.
