Mechanics: Unit 2 Forces (class) Flashcards
What are the two effects of force?
- change the state of motion of a body
2. deform a body
What is the SI unit of force?
the newton (N)
What is one newton equal to?
1kg m/s2
What is statics?
forces acting on bodies which are at rest or moving with constant velocity ie. not accelerating
Which type of body cannot be deformed?
rigid body
What is the difference between mass and weight?
mass is the amount of matter in a body whereas weight is the force of gravity on a body
How do we calculate weight?
mass (kg) x gravity (m/s2)
What unit do we use to measure weight?
a newton
What is gravity?
the acceleration due to an attraction between masses depending on the size of the mass and the distance
Which of mass and weight remains constant?
mass
What is pressure?
force per unit area
What is the derived SI unit for pressure?
a pascal (Pa)
What is a pascal equal to?
1N/m2
What is density?
mass per unit of volume
What symbol is used for density?
ρ - the greek letter rho
What is density measured in?
kg/m3
What is the density of water?
1000kg/m3
give an equation that links gravity, height, pressure and density
P = p g h pressure = density x gravity x height
What is the difference between P and p?
P is pressure
p is density
What is friction?
a force between surfaces that opposes motion
What do we measure friction in?
newtons
What is friction
a) dependent on?
b) independent of?
a) roughness of the surface and size of force
b) apparent contact area
What is friction force equal to?
μ (friction coefficient) x normal force
What is the friction coefficient?
the measure of the maximum friction force between two surfaces