Topic 5 - Forces Flashcards
What is a vector quantity?
Quantities that have magnitude and direction
What is a scalar quantity?
Quantities that have magnitude only
What is magnitude?
Size
Give 3 examples of a vector quantity.
Force
Velocity
Displacement
Give 3 examples of a scalar quantity.
Speed
Distance
Mass
How are vector quantities represented?
Arrows - length represents magnitude and direction shows direction of quantity
Define force.
A force is a push or pull on an object that is caused by interacting with something
What is a contact force?
The objects must be physically touching
What is a non-contact force?
The objects are physically separated
Give 3 examples of a contact force.
Friction
Air resistance
Tension
Give 3 examples of a non-contact force.
Gravitational force
Electrostatic force
Magnetic force
Is force a vector or scalar quantity?
Vector
What happens when two objects interact?
They exert a force on each other
What is an interaction pair?
A pair of forces that are equal and opposite and act on two interacting objects
What is weight?
The force acting on an object due to gravity
Why is there gravity in earth?
Due to the gravitational field around the earth
What does the weight of an object depend on?
The gravitational field strength at the point where the object is
How do you calculate weight?
Weight (N) = mass (kg) x gravitational field strength (N/Kg)
W=mg
Where is the weight of an object held?
The weight of an object may be considered to act at a single point referred to as the objects “centre of mass”
What is the relationship between weight and mass?
Weight and mass are directly proportional
What device can be used to measure weight?
A calibrates spring balance or newtonmeter
What is the resultant force?
The overall force on a point or object - a number of forces acting on an object may be replaced by a single force that has the same effect as all the original forces acting together
How do you calculate resultant force?
Add forces in the same direction and subtract forces in the opposite direction
How do you show all the forces acting on an isolated object?
Free body diagrams