P5 - Forces Flashcards
What is a scalar?
A magnitude.
What is an example of a scalar?
Mass, speed, distance.
What is a vector?
A magnitude and a direction.
What is an example of a vector?
Velocity, weight, acceleration.
What is a contact force?
A force that only occurs when objects are in contact.
What is a non-contact force?
A force that doesn’t require contact for a force to be acted on it.
What is the resultant force?
The sum of all the forces acting on an object.
How do you calculate the force acting on a spring?
Force (N) = spring constant (N/m) x extension (m)
What is the limit of proportionality?
The point at which Hooke’s law no longer occurs and the length of the spring gradually increases without a force being added.
What is Hooke’s law?
Weight is proportional to the amount an object is being stretched.
What is elastic/plastic deformation?
When an object is stretched beyond the limit of proportionality, so that it can’t return to it’s original state.
What is inelastic deformation?
When an object is stretched within the limit of proportionality, so that it can return to it’s original shape.
What is a moment?
The turning effect caused by applying a force at a distance from the pivot point.
How do you calculate a moment?
Moment (N/m) = force (N) x distance (m)
What distance measurement is used when calculating a moment?
The perpendicular distance from the pivot, to the line of action from the force.
What is an equation that links pressure, force and area?
Pressure = force / area
What equation shows the magnitude of pressure in liquids at different depths?
Pressure = column height x density of liquid x gravitational field strength
What happens when the upthrust = weight of object?
Up and down forces are balanced. Object will stay still.
What happens when upthrust is less than the weight of the object?
Down force is greater than up force. Object will sink.
Explain upthrust in terms of density.
It is more dense towards the bottom.
More particles are colliding with object.
More force exerted on object. Object forced up.
What is an average speed?
The speed of an object measured over the whole journey.
What is an instantaneous speed?
The speed of an object at the very instance of being measured.
How do you calculate average speed?
Average speed = distance travelled / time taken
What does the gradient of a distance time graph give you?
The speed.