Work and Energy Flashcards
What is work?
work occurs when a force causes the displacement (change in position) of an object; if the object has not moved (in the same direction as the force), work was NOT done by the force
What is acceleration?
how much an object is speeding up or slowing down (the rate at which an object’s velocity changes with respect to time)
What is displacement?
a change in position (direction matters)
example: two steps forward and two steps back is a displacement of 0 steps
What is distance?
total travel (direction does NOT matter) example: two steps forward and two steps back is a distance of 4 steps
What is the acceleration due to gravity on Earth (g)?
g = 9.8 m/s² (sometimes rounded to 10 m/s²)
What is the formula for acceleration?
acceleration = change in velocity ÷ time
What is the formula for kinetic energy (KE)?
kinetic energy = ½ ⋅ mass ⋅ velocity²
KE = ½mv²
What is the formula for mechanical energy?
mechanical energy = potential energy + kinetic energy
ME = PE + KE
What is the formula for momentum?
momentum = mass ⋅ velocity p = mv
What is the formula for potential energy (PE) due to gravity?
potential energy = mass × acceleration due to gravity × height
PE = mgh
What is the formula for power?
power = work ÷ time
P = W/t
units: watts = joules ÷ seconds
What is the formula for speed?
speed = distance ÷ time
direction does NOT matter
What is the formula for velocity?
velocity = displacement ÷ time
v = d/t
(direction matters)
What is the formula for work?
work = force ⋅ distance W = Fd (joules = Newtons ⋅ meters)
What is the SI unit for acceleration?
meters per second² (m/s²)
What is the SI unit for distance or displacement?
meter (m)
What is the SI unit for energy?
joule (J)
What is the SI unit for force?
Newton (N)
What is the SI unit for power?
watt (W)
What is the SI unit for time?
seconds (s)
What is the SI unit for velocity?
meters per second (m/s)
What is the SI unit for work?
joule (J)
What is the work-energy theorem?
Work done by an external force on an object changes the object’s mechanical energy, so:
work = change in potential energy
(the object was raised or lowered)
AND/OR
work = change in kinetic energy
(the object’s velocity increased or decreased)
What is velocity?
how fast an object is moving (the rate at which an object’s position changes with respect to time); if an object is not moving, its velocity is 0 m/s
What is power?
the rate at which work is done with respect to time
What is the formula for impulse?
impulse = force ⋅ time impulse = mass ⋅ change in velocity
What is kinetic energy?
the energy of motion; if an object is not moving, its kinetic energy is 0 joules
What is potential energy due to gravity?
the energy stored because of an object’s position above the ground; if an object is on the ground, its potential energy is 0 joules
