Chapter 5 work energy and power Flashcards
What is the equation for work done?
Work done = Force × displacement × cos(θ)
W=Fdcosθ
What are the units of work and energy?
Joules (J)
What is 1 joule equal to?
The work done when a force of 1 newton moves an object 1 metre in the direction of the force.
What is the principle of conservation of energy?
Energy cannot be created or destroyed, only transferred or transformed.
What is kinetic energy?
Energy due to motion:
E_k = 1/2 mv²
What is gravitational potential energy?
Energy due to height above ground:
E_p = mgh
What is the equation for power?
Power = work done / time
P = W/t
What are the units of power?
Watts (W), where 1 W = 1 J/s
What is the equation linking power, force, and velocity?
P = Fv
(only if motion is at constant speed in the direction of the force)
Define efficiency.
Efficiency = (useful energy output / total energy input) × 100%
What causes energy to be wasted?
Friction, heat loss, sound, and other forms of dissipation.
What is elastic potential energy?
Energy stored in a stretched or compressed object:
E = 1/2 kx²
Where k is the spring constant and x is extension.
What is meant by mechanical work?
Work done by a force moving an object.
What is meant by electrical work?
Work done when charge flows in an electric circuit.
