Mechanics 4 - Work and Energy Flashcards
Is energy a more recent concept?
Yes, developed in the 1800s as opposed to kinematics and Newton’s laws by 1700s
What should you do if motion question looks complicatied?
Use energy Equations
Why is E important?
It is a more abstract concept, so once you understand it, it can cover a lot of topics
Conservation of energy
In a closed system, energy is trasnformed and transferred from one object to another, hence conserving E in that system
Definition of work
When F is applied on an object and it moves a certain distance in a certain direction, W is done on that object
W formula
Fd in Joules (J)
Is work a property?
Work is not a property of the object but an interaction. This interaction, like force, involves transfer of E.
What are work calculations independednt of?
W is interaction of A on B so it doesn’t account for effect of Friction or if the object B is accelerating
Does displacement have to be in the same direction for W?
No Force can act at an angle so we need the horizontal component of the force vector which F cosø
W = F cosø x d
Relationship between Ek, F and W
Kinetic Energy is the property of the object transferred by force and the amount of E is the work done by force.
EKf =
EKi + W
Kf = ?
EKf = 1/2 mvˆ2
What is PE?
Energy that is stored because of an objects position
What is GPE
Work is required to raise an object against Earth’s gravity, now it has PE
When F is perpendicular to displacement…
Work done is 0
