Mechanics Flashcards
What is a vector?
A quantity with direction as well as magnitude
What is scalar?
A quantity with only magnitude (no direction)
What must be true of the 3 force vectors acting on a particle in order for the particle to be in equilibrium?
They must form a closed vector triangle
Define moment
Force x perpendicular distance between the line of action of the force and the point.
What is the principle of moments?
For a system in equilibrium, the sum of the clockwise moments is equal to the sum of the anti-clockwise moments, about any given point
What is a couple?
A pair of equal and opposite forces acting on a body, but not along the same line.
What are the 2 conditions for an object to be in equilibrium?
No net force and no net moment
What is meant by the centre of mass of an object?
The single point that you can consider all the weight of the object to act through
Newtons First law ?
Objects remain at constant velocity unless acted on by a resultant force
Newtons Second law?
Force= mass x acceleration
Newton’s third law
If an object A exerts a force on object B, then object B exerts an equal but opposite force on object A
How is drag linked to velocity?
Drag is proportional to v^2
If there is no air resistance what happens to the horizontal component of velocity in projectile motion?
It remains constant
What is the principle of the conservation of linear momentum?
Total momentum before a collision= total momentum after the collision, provided no external forces act
What condition needs to be met for momentum to be conserved?
No external forces act on the particles
