1 - 2 Forces and shape
● ***Forces: “pushes & pulls”
● Mass ≠ weight: mass does not change, while weight changes according to
gravitational force of planet; ***∴ W (weight [N]) = m (mass [kg]) * g
(gravitational field strength [N/kg])
○ ***Force of 1 N makes mass of 1 kg accelerate at 1 m/s2
Scalars and vectors
● Scalars have magnitude ONLY, e.g.:
○ Speed
○ Distance
○ Energy
○ Time
○ Volume
○ Density
○ Mass
● Vectors have BOTH magnitude and direction, e.g.:
○ Acceleration
○ Displacement (complementary to)
○ Velocity (complementary to)
○ Force (weight)
○ Momentum
○ Moments\of force
List of forces
● ***Friction (tends to oppose motion when two surfaces are sliding or trying to slide)
● ***Gravity (重力) (attractive force between two masses)
● ***Weight (gravitational force [萬有\引力//重力場] on an object from a
planet/moon)
● ***Normal reaction force/Contact (“force that prevents everything from falling down
due to gravitational force”)
● ***Electric (electrons)
● ***Electrostatic (靜電) (between charged objects)
● ***Magnetic (磁性) (between magnetic objects)
● ***Thrust (推力) (driving force from an engine)
● ***Air resistance/Drag force (空氣\阻力) (opposes motion)
● ***Tension (張力) (in any stretched spring or string)
● ***Upthrust/Lift (上沖) (upward push on floating objects)
○ ≠ buoyancy (浮力)
● ***Nuclear (acting between protons and neutrons - as they are both nucleons)
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● ***Forces: “pushes & pulls”
● Mass ≠ weight: mass does not change, while weight changes according to
gravitational force of planet; ***∴ W (weight [N]) = m (mass [kg]) * g
(gravitational field strength [N/kg])
○ ***Force of 1 N makes mass of 1 kg accelerate at 1 m/s2
Scalars and vectors
● Scalars have magnitude ONLY, e.g.:
○ Speed
○ Distance
○ Energy
○ Time
○ Volume
○ Density
○ Mass
● Vectors have BOTH magnitude and direction, e.g.:
○ Acceleration
○ Displacement (complementary to)
○ Velocity (complementary to)
○ Force (weight)
○ Momentum
○ Moments\of force
List of forces
● ***Friction (tends to oppose motion when two surfaces are sliding or trying to slide)
● ***Gravity (重力) (attractive force between two masses)
● ***Weight (gravitational force [萬有\引力//重力場] on an object from a
planet/moon)
● ***Normal reaction force/Contact (“force that prevents everything from falling down
due to gravitational force”)
● ***Electric (electrons)
● ***Electrostatic (靜電) (between charged objects)
● ***Magnetic (磁性) (between magnetic objects)
● ***Thrust (推力) (driving force from an engine)
● ***Air resistance/Drag force (空氣\阻力) (opposes motion)
● ***Tension (張力) (in any stretched spring or string)
● ***Upthrust/Lift (上沖) (upward push on floating objects)
○ ≠ buoyancy (浮力)
● ***Nuclear (acting between protons and neutrons - as they are both nucleons)
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