Flashcards in Topic 2.2: Forces and Dynamics Deck (15):
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
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.
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.
o UPTHRUST: An upward force on a body which is immersed in a fluid (liquid or gas).
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.
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.
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.