3.2 - Forces in Action (missing density, pressure, archimedes) Flashcards
What is 1 newton defined as?
The force that will give a mass of 1kg an acceleration of 1ms2
Define the weight of an object.
The gravitational force acting upon the object through its centre of mass.
Define friction.
The force arising when two surfaces rub against each other.
Define drag.
The resistive force on an object travelling through a fluid (air/water)
Define tension.
The force within a stretched cable/rope.
Define upthrust.
The upward buoyancy force acting on an object when it is in a fluid.
Define the normal contact force.
Force arising when an object rests against another object, acting perpendicular to the plane of contact.
What are the factors that the magnitude of a drag force on an object depends on?
- Speed
- Cross sectional Area
- Shape/Texture of object
- Density of fluid
Drag is proportional to the square of speed. What does this mean for an object in free fall?
The drag force increases until it has the same magnitude as the weight, resulting in terminal velocity.
Define the moment of a force?
Magnitude X perpendicular distance from force to pivot point.
What kind of effect is the moment of a force?
The turning effect of the force about an axis/pivot.
In terms of moments, what happens if the force is acting parallel to the pivot, or on the pivot?
A moment is not produced.
What is a couple?
Two equal and opposite forces that are parallel with each other but not on the same straight line.
What happens if a couple acts on an object?
It rotates in position.
What is the moment of the couple called?
Torque
