Kientic Energy and Work Flashcards
What is kinetic energy?
It is associated with the motion of a particle of mass m and speed v, where v is well below the speed of light, is K = ½mv2. (State of motion of an object).
What is energy?
A scalar quanity that associates with the state (or condition) of one or more objects.
What is the principle of energy conservation?
Energy can be tranformed from one type to another and transferred from one object to another, but the total amount is always the same (energy is conserved).
What is work?
Work is energy transferred to or from a system by means of an external force acting on that system.
W = ∫F·dr, for a variable force F.
Derive the relationship between work and KE.
Suppose Fx = max.
v2 - vo2 = 2dax
⇒ W = ΔKE.
What is the work done by an applied force as a particle-like object is either lifted or lowered related to the work done by the gravitional force? Assume the particle starts and finishes at rest.
Wa+Wg = 0
⇒ The applied force trasfers as much energy to the object as the gravitional force transfers from it.
What is the work done by the gravitional force?
W = F·Δy = mgycosØ, since F is constant and Ø is the angle between F and displacement.
Define Hooke’s law.
Fs = -kd, where d is the displacement of the spring’s free end from its position when the spring is in its relaxed state (neither compressed nor extended), and k is the spring constant (a measure of the spring’s stiffness.)
A spring force is thus a variable/constant force: It varies with the displacement of the spring’s free end.
variable.
What is the work done by a spring force?
Ws = -k∫xdx = ½k[xi2 - xf2]
Define Pavg.
Pavg = W/Δt
Define Pinst., give 2 definitions.
Pinst. = dW/dt = F·v
A block moves with uniform circular motion because a cord tied to the block is anchored at the center of a circle. Is the power due to the force on the block from the cord positive, negative, or zero?
Zero, since tension is perpendicular the path of block.
GIve 2 approaches to this problem.
