physics

• imp:


  -to convert a larger unit to a smaller unit we multiply and to convert a smaller unit to larger we divide

  -area under the graph=distance covered by the object or body

  -gradient of distance-time graph shows speed and gradient of speed time graph shows acceleration
• rest and motion and uniform speed

  rest: a body is said to be at rest if it doesnt not change its position with respect to its surroundings

  motion: a body is said to be in motion if it changes it position with respect to its surroundings

  uniform speed: equal distance is covered in equal intervals of time

  non-uniform speed: unequal distance covered in equal intervals of time
• formulae


  fm

  
• formulae 2 


  fm

  
• acceleration and deceleration

  acceleration: rate of change in velocity ,with time

  deceleration: decrease in velocity with time
• forces and motion:

  -when a body of mass of 1kg is moved with the acceleration of 1m\s^2 than force produced will be 1 newton

  -air resistance or drag: if object moves through air or water

  -upthurst: upward part of liquid

  -friction: when 2 objects rub together

  -centripetal force: a force which causes objects to move in circular path,its always taken towards the center of the circular path

  -net force: difference or addition of 2 or more forces

  -EARTH:9.8N\Kg MOON:1.6N\Kg

  -acceleration due to gravity: in the absence of air resistance all objects fall t the ground with acc of 9.8m/s^2
• forces and motion 2

  -free fall: when there is so air and the only force acting is weight

  -TERMINAL VELOCITY: maximum constant velocity attained by a body while falling through a fluid.

  -impulse: force that acts for a short time and has a huge impact.

  -when a car is moving it has high momentum and if it bumps into another car its momentum is lowered, the bump happens in matter of seconds, using seat belt saves the drivers life as it will be protecting u to strike to any parts of the car at the same time and less injuries will be there

  -crumple zone: absorbs energy caused due to accidents
• moment(torque):


  -turning effect of a force about a pivot(point) is known as moment of a force

  -principle of moment: sum of clockwise = sum of anticlockwise

  -if force is applied at pivot no moment is produced

  -equilibrium: net force should be zero and net moment should be zero

  -COG(center of gravity):a point where entire weight of the body seems to be acting.

  -COM(center of mass): a point where entire mass of the body seems to be acting

  -stability depends on: if center of gravity is lowered, if area of contact is more
• forces and matter

  -elastic material: regains size after removal of force

  -plastic material: doesnt regain size after removal of force

  -extension: difference btw new length and original length

  -Hookes law: extension produced in a spring is directly proportional to the load provided , limit of proportionality is not crossed

  -limit of proportionality: point on the graph up to which Hookes law is obtained and the line is straight.

  -after limit of proportionality is crossed the spring will be completely deformed and wont regain size even if loads are removed
• forces and matter

  pressure:

  more pressure is exerted from solid material(more weight)

  atmospheric pressure=1X10^5 Pa

  liquid pressure= P=p(density)Xg(gravity)Xh(height)

  SI UNIT OF AREA = m^2
• transfer of energy

  -internal energy: sum of kinetic and potential energy

  -energy: ability to do work

  -gravitational potential energy: energy processed by a body due to its position

  -kinetic energy: energy of a moving object

  -electrical potential\strain energy: when elastic material is compressed or stretched.

  -nuclear energy: energy stored in the nucleus of an atom

  principle of conservation: in any energy transfer the total amount of energy before and after transfer is equal
• energy resources


  3 sources that dont use suns energy?

  tidal nuclear geothermal

  Fission? process in which big nucleus is broken into smaller nuclei with release of energy

  Fusion? 2 small nuclei form a big nucleus
• work?


  -when a force applied on an object and the object moves in the direction of the force.

  -work done= energy transferred

  -if force and displacement are more then work is more
• power?


  -rate of work done or rate of energy transferred

  1 horse power=746 watts

  kilo=10^3

  more power= more energy consumed