Forces Flashcards
(19 cards)
What is the centre of mass of an object?
The point at which the weight can be assumed to act.
What does the weight of an object depend on?
It’s mass and the gravitational field strength
(W=mg)
What is a free-body diagram?
It is a diagram showing the set of forces acting on a single object.
What is weight?
The force due to gravity that acts through an objects centre of mass.
What is friction?
The force that acts between two surfaces in contact to oppose motion.
What is drag?
The resistive force that acts on an object moving through a fluid
What is tension?
The force within a stretched object such as a cable or rope.
What is upthrust?
The upward buoyant force that acts on an object in a fluid.
What is a normal contact force?
A force that acts perpendicular to a surface when an object rests on it.
How do you calculate the component of weight down a slope?
W sin θ or mg sin θ
(where θ is the angle between the slope and the horizontal)
What are the 2 key factors in determining the magnitude of drag force acting on an object in a fluid?
Speed and cross-sectional area
What is terminal velocity?
The maximum speed reached by a falling object when drag and weight are equal.
What is a triangle of forces?
A vector diagram of the three forces acting on an object in equilibrium.
What is a resultant/net force?
The vector sum of forces acting on an object
What is Newton’s 1st Law of motion?
An object will remain at rest or move at a constant velocity unless acted upon by a
resultant force
What is Newton’s 3rd Law of motion?
When two objects interact they exert forces on each other that are equal in magnitude, opposite in direction and of the same type of force.
What is Newton’s 2nd Law of motion?
Resultant force acting on an object is proportional to its rate of change of momentum,
and is in the same direction.
What two sets of units can be used for momentum?
Ns or kgms-1
How is the momentum of an object calculated?
mass x velocity
