Physics Yr 11 Term 1

• To calculate µ:$µ =$$frictional force/normal force$
• To find mew:

  Step 1: find the weight of the object, weight = mass • gravity

  Step 2: using the weight, find the normal force which is same magnitude as weight, however, opposite direction

  (For next step, frictional force should be given)

  Step 3: plug it into the equation of mew= frictional force/normal force
• Static friction ≥ kinetic friction
• Amount of minimum force over time required in the sense of friction

  
• Accuracy: the amount of error (can be percentage or absolute) in an experiment, also referring to how sensititive the measuring device used was
• Percentage error:

  
• Reliability: Conducted the experiment multiple times AND achieved similar results each time
• Validity: most amount of controlled variables were kept throughout the experiment and the experiment took the appropriate measure to reach the hypothesis
• Accuracy, validity, and reliability are only used for discussions in a report/depth study/discussion question
• Newton's first law: law of inertia, any object at rest or in motion will stay in rest or motion unless acted on by an external unbalanced force
• Newton's second law: Force = mass • acceleration
• Newton's third law: every action has an equal and opposing reaction
• For qualitative answers, ensure to use: 1. Effect: the experiment which was conducted

  2. A conjunction: "this happened due to" "because" "as a result of"

  3. Cause: the most relevant corresponding law(s) which reinforce the statement
• For Force = mass • acceleration, ensure that mass is in kg, and acceleration is in m/s² for force to be in newtons
• A force is always a vector. It can be,

  Contact and non contact
• Adding vectors in 1D: you have single digit IQ of you can't do this
• Adding vectors in 2D:

  For magnitude: use Pythagoras' theorem

  For direction: use tan-¹
• DT, VT, AT


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• Speed: distance/time

  Velocity: displacement/time
• Absolute error: experimental value - theoretical/true value
• s: displacement

  u: initial velocity

  v: final velocity

  a: acceleration

  t: time
• Relative motion in 1D: basically adding vectors in 1D
• Relative motion in 2D: V(B rel A) V(BG) - V(AG) OR JUST STATED AS, V(B)- V(A) draw a vector diagram according to this
• V(B rel A) = -V(A rel B)
• In third perspective views, from a floating observer, simply do vector addition in 2D
• To resolve vectors, simply find X and y value for them, so, for horizontal component, it is Fcostheta, for vertical components, it is Fsintheta
• For object thrown up, vertical motion shows as follows:

  When object drops, a = 9.8 m/s²

  When object's s value is max, v = 0

  When object falls to the ground or thrower's hand, v = 0 and s = 0
• What is velocity and displacement when an object goes back to rest?

  v = 0 and s = 0
• In inclined planes, normal force is mgcostheta, acceleration downwards is mgsintheta. If the object is not moving, then the acceleration is either less or equal to the static friction.
• Mew in inclined plane is simply tantheta
• If the object on an inclined plane is attached to a string, the tension in the string is the same as the acceleration (mgsintheta)
• Static equilibrium: object is at rest, unmoving

  Dynamic equilibrium: object has a constant velocity, moving

  For both, the net force will still be 0
• When object is at rest, is friction static?
• Static equilibrium: object is at rest, with Net force =0
• When object is in static equilibrium,

  1. estabush all forces = 0

  2. Resolve the vectors of T, & T₂

  3. Establish that vertical vectors of T, & T₂ added = mg

  4. Establish that (generally) horizontal vectors equal each other

  5. Manipulate the equation to isolate one T and substitute that into the vertical equation

  6. Use mg. to find the answer
• Forces in systems. ex pulleys, assume no friction in them
• Tension is on all sides of the string in pulleys
• When the object & moving, in a pulley system that is off a bench, F= ma, however, F=m₂g(since that is the net force) and m=(m₂+m1) and a is usually what is found in such equations
• Tension for forces in systems usually refers to T = W-Fnet
• For suspended masses: 


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