Topic 2.2: Forces and Dynamics Flashcards
Define weight
the force of gravity on a body
What are the components of Free-Body Diagrams?
its weight acting vertically from the center of mass
all forces where it is contact with other objects
any magnetic or electrostatic forces
Define friction
o FRICTION: The force which opposes motion when one surface moves over another. It is caused by the roughness of the surfaces.
Define normal reaction
o NORMAL REACTION: Two objects in contact each exert a force on the other which is perpendicular to the surface.
Define tension
o TENSION: A force produced in a body when opposing forces are stretching it. The opposite is a compression force when two forces are squashing a body.
Define upthrust
o UPTHRUST: An upward force on a body which is immersed in a fluid (liquid or gas).
Define lift
o LIFT: An upward force on the wing of an aircraft due to the air flowing around it.
• 2.2.4: State Newton’s first law of motion
o NEWTON’S FIRST LAW OF MOTION: A body continues to maintain its state of rest or of uniform motion in a straight line unless acted upon by an external unbalanced force.
Define inertia
o INERTIA: The property of matter which makes it resist acceleration; objects’ resistance to change
• 2.2.6: State the condition of translational equilibrium
o TRANSLATIONAL EQUILIBRIUM: When the net force on an object is zero in all directions (ie no linear acceleration).
• 2.2.8: State Newton’s second law of motion
o NEWTON’S SECOND LAW OF MOTION: ∑F = ma The rate of change of momentum of an object is proportional to the applied force and takes place in the direction in which the force acts.
Define impulse
o IMPULSE: The change in momentum. A vector. Unit is Ns
Define linear momentum
o LINEAR MOMENTUM: the product of mass and velocity. It is a vector measured in kgms-1
• 2.2.12: State the law of conservation of linear momentum
o LAW OF CONSERVATION OF LINEAR MOMENTUM: The momentum of an isolated system remains constant (ie when no external forces are acting). Or, in any isolated system, the change in momentum is zero.
State Newton’s third law of motion
o NEWTON’S THIRD LAW OF MOTION: Whenever a particle A exerts a force on another particle B, B simultaneously exerts a force on A with the same magnitude in the opposite direction
