Work,energy And Power Flashcards
What is the equation for weight?
Weight = mass * gravity
What is the normal reaction (contact force) ?
Normal reaction is when it acts normal (perpendicular) to the surface.
It’s called a normal reaction because it has reacted to the forces in the opposite direction.
What symbol is used for normal reaction?
R or maybe N
What is Newton’s first law?
An object will remain at rest or will continue to move with constant velocity unless acted upon by external force
What is Newton’s second Law?
An object will accelerate if there is an overall resultant force on the object. The acceleration is proportional to this force, and inversely proportional to its mass.
F = ma
F = resultant force
What is maximum friction?
Maximum friction = coefficient of friction (u) *normal reaction (R)
Fr = UR
Coefficient > 0
Less than 1.5
What are the 2 facts about friction?
- Friction acts in the opposite direction to its motion
- Friction can be less than this maximum value if the particle is not moving
What is the limiting equilibrium?
Limiting Equilibrium is when frictional contact force is maximum, which happens when the object is at the point of sliding or moving
List 3 facts about work
- if an object has energy, it can do work
- work transfers energy from one place or form to another
- work is done by a force when it moves an object
What is the equation of work?
Work (a bit like energy) = force * distance
Force and distance must be in the same direction
What is work measured?
Work is in joules (J)
Is the speed is constant what does that mean?
It means there is no acceleration.
And the forces are equal to each other.
What is the equation for work done against gravity?
W.d = mgh
What is the energy put into system?
The pulling forces puts the energy in P the distance the particle moves. (pd)
What does this energy get spent on (three things)?
- w.d. Against friction Fr * D
- w.d. Against gravity mgh
- increasing the kinetic energy
