Forces (Moments, Hooke's Law, Mechanical Quantities)
- Created by: Jasmine Tw
- Created on: 25-04-22 18:53
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- FORCES
- MECHANICAL QUANTITIES
- Vector
- Magnitude and direction
- e.g. velocity, force, displacement
- Scalar
- Magnitude only
- e.g. time, distance, seed
- Centre of mass
- The single point where an object's weight is said to act
- Resultant force
- sum of all forces in all directions acting on an object
- found by adding/subtracting forces acting along a straight line
- Weight
- larger the mass, stronger the field, greater the attraction
- measured by a newton meter/calibrated spring-balance
- gravitational attraction
- W=mg
- g=0.8 N/kg on Earth
- Vector
- HOOKE'S LAW
- Elastic potential energy
- Ee = ½ ke^2
- 1 J = 1 Nm
- W=Fs
- also applies to compression
- Ee = ½ ke^2
- Force is proportional to extension up to the limit of proportionality
- F = ke
- e = extension (m)
- k = spring constant (Nm^-1)
- Deformity
- Elastic deformity
- return to original shape when load removed
- Plastic deformity
- Does not return to original shape when load removed
- spring is pulled too far
- Does not return to original shape when load removed
- changing shape
- Elastic deformity
- F = ke
- Work done
- against friction, causes increase in temp. of object
- Work is done when a spring is stretched/ compressed
- more than one force is applied
- when energy is transferred from object doing the work to another form
- Elastic potential energy
- Moments
- turning effect of a force around a pivot
- M = Fd
- d is perpendicular to the line of action (m)
- M = moment (Nm)
- clockwise moment = anticlockwise moment
- M = Fd
- Equilibrium
- clockwise moment = anticlockwise moment
- Gears
- Alter force + speed
- High gear
- Large gear drive small gear
- rotates faster & smaller moment
- Large gear drive small gear
- Low gear
- Small gears drive large gears
- Large gears rotate slowly & larger moment
- force applied is further away from pivot
- momentum of large gear is greater
- force applied is further away from pivot
- Large gears rotate slowly & larger moment
- Small gears drive large gears
- Levers
- act as force multiplier
- make up by load, effort, pivot
- increases a provided force
- effort to pivot > pivot to load
- force applied on load is greater to reach equilibrum
- turning effect of a force around a pivot
- MECHANICAL QUANTITIES
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