Mechanics Flashcards
What is the difference between a scalar and a vector quantity?
vectors have direction whereas scalars don’t
Is speed a scalar or vector?
scalar
Is velocity scalar or vector?
vector
Is distance scalar or vector?
scalar
Is displacement scalar or vector?
vector
What is Newton’s first law?
An object will remain at rest or at constant velocity unless acted on by an external force
What is Newton’s second law?
F=ma
What is Newton’s third law?
if object A exerts a force on object B, object B will exert an equal but opposite force on object A
When is an object at equilibrium?
When all vertical forces are equal and all horizontal forces are equal, the object will remain at rest or constant velocity
How do you resolve the vertical component of a vector?
Rsin(x) where x is the angle between the vector and the horizontal.
How do you resolve the horizontal component of a vector?
Rcos(x) where x is the angle between the vector and the horizontal.
What is a couple?
a pair of equal and opposite forces acting on a body but not along the same line
How do you calculate a moment?
moment = force x perpendicular distance from the pivot along the line of action
State the principle of moments.
when in equilibrium the total sum of the anti clockwise moment is equal to the total sum of the clockwise moment
What is the centre of mass?
the point at which all mass of the object acts