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physics - p2 - Coggle Diagram
physics - p2
forces
scalars - magnitude - speed, distance, mass
vector - magnitude and direction - velocity, displacement
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Free body diagrams
contact force means the objects must be touching eg push, pull - friction
non contact force - two objects that aren't touching, electrostatic, magnetic and gravitational forces
Resultant force is the overall effect of the forces, whether it accelerates, decelerates or stays the same.
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Normal contact force (up) - drag (back) - thrust (forward) - weight ( down ) - friction (opposite direction)
newtons laws
1st law - an object will remain stationary or at constant speed unless acted upon by an external force.
2nd law - the force acting on an object is equal to its rate of change in acceleration. Force = mass x acceleration
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Experiment for 2nd law - acceleration of trolley on an air track. the force acting on the trolley is equal to the weight. measure time and speed going across track
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Scale diagrams
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Equilibrium means all forces are balanced or zero resultant force, it is in equilibrium.
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Time graphs
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Velocity time graph - gradient = acceleration, area under graph is distance travelled.
momentum
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when a resultant force acts on an object for a certain period of time, it causes a change in momentum. The faster the change in momentum, the bigger the force
Hookes law
hang spring in clamp, measure springs length with ruler. weigh your masses and add them on one at a time. as each mass is added measure the length of the spring. then calculate the extension= new length - original length
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moments
Turning effect of a force. if a force acts on an object with a pivot, it can rotate. The force on the spanner causes a turning effect. larger spanner means larger moments
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Terminal velocity
the greater the drag, the lower the terminal velocity. skydiver, the driving force is his weight due to gravity and the drag. without parachute, skydivers area is small. Parachute open more air resistance as larger area but the driving force is the same. terminal velocity is much smaller to hit the ground
hydraulics
used as force multiplyers. system has 2 pistons one with a smaller cross sectional area than the other. pressure is transmitted equally so both pistons is the same.
Inertia - measure of how difficult it is to change an objects velocity. depends on mass, larger the mass, the larger the inerta.
conservation of momentum - in a collision , when no external forces act, momentum is conserved.
elastic collision - total energy in kinetic energy stores is the same before and after the collisions. inelastic collision - some of the energy in the kinetic energy store is transferred to other stores.
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