forces revision for test Flashcards
which quantities are called scalars?
scalars only have size (magnitude)
A quantity known as a vector has
both size and direction
We call a force a contact force if
the objects are physically touching, for example:
air resistance, tension and frition
We call a force a non contact force if
the objects are physically separated, for example:
gravitational force, electrostatic force and magnetic force.
What is weight?
weight is the force acting on an object due to gravity.
Is gravitational field strength greater on a smaller or more massive object?
massive.
All matter has a gravitational field strength, it is greater the more mass an object has.
Weight of an object and the mass of an object are directly proportional, we calculate it using the formula..?
weight = mass x gravitational field strength.
W=mg
Is mass a scalar or vector quantity?
scalar (has size only)
Is weight a scalar or vector quantity?
vector (size and direction)
What is the unit of weight?
newtons, N
What is the unit of mass?
kilograms, Kg
What is resultant force?
equals the total effect of all the different forces acting on an object.
What is work done?
Work is done when a force causes an object to move.
What is the work done equation?
work done = force x distance moved along the line of action of the force.
What is work done measured in?
joules, J
What is force measured in?
newtons, N
What is the weight of a 67g object in a gravitational field strength of 10N/kg?
0.067 Kg x 10 = 0.67N
What is 78Nm in joules?
78J
One joule of work is done when a force of one newton causes a displacement of one metre.
1 joule = 1 newton metre
How can you calculate force on a spring?
force (N) = spring constant (Nm) x extension (m)
How is work done on a spring stored?
it is stored as elastic potential energy
What is Hookes Law?
The extension is directly proportional to the stretching force.
What is the force of a spring with an extension of 0.1 m and a spring constant of 2N/m?
0.1 x 2 = 0.2N
What happens to a spring that is taken beyond it’s limit of proportionality?
it is permanently deformed.
What is compression?
the act of pushing particles together
What is tension?
the particles are pulled further apart.
What is inelastic stretching?
this is when an object does not return to its original length after the force has been removed.
