Work and Kinetic Energy Flashcards
Quantity that can be converted from one form to another; involved in all interactions leading to changes in state (phase changes or changes in state of motion); a scalar quantity
Energy
SI Unit of energy
Joule
Two types of mechanical energy
Kinetic and Potential
Energy that objects possess due to their motion
Kinetic Energy
Formula for Kinetic Energy
K=1/2mv^2 (where m is mass, and v is speed)
Energy transferred to the object via the application of force along a displacement; energy in motion; scalar quantity
Work
SI unit of Work
Joule
T or F. You do not do work by exerting a force on a body while it moves from one place to another.
F. You do work by exerting a force on a body while it moves from one place to another.
Formula for Work
W=Fs (force times displacement); W=Fscosθ
Can work be zero?
Yes. Work can be (+), (-), or 0.
How does work become positive?
If the force has a component in the direction of the displacement
How does work become negative?
If the force has a component opposite the direction of the displacement
How does work become zero?
If the force is perpendicular to the direction of the displacement
Is there work being done on a box sliding freely along a ramp?
None. If it is being pushed, then there is work.
Formula for Work-Energy Theorem
W = Kf-Ki = ΔK (Net work done on an object equals the object’s change in kinetic energy.)
If work is positive, Kf > Ki, speeding ______.
up
If work is negative, Kf > Ki, speeding ______.
down
If Ki=0, W = ______.
Kf. KE of an object is equal to the total work that was done to accelerate it from rest to its present speed.
How to compute for work and energy with varying forces?
Sum of the areas under the curve approximates the total work done
Amount of energy transferred or converted per unit time; scalar quantity
Power
SI unit of Power
Watt [W] = [Joules/sec]
English system unit of Power
horsepower
Conversion factor of horsepower
1 HP = 735.7 Watts
Formula for average Power
Pave = ΔW/Δt
