FOLLOW US ON TWITTER
SHARE THIS PAGE ON FACEBOOK, TWITTER, WHATSAPP ... USING THE BUTTONS ON THE LEFT


YOUR PARTICIPATION FOR THE GROWTH OF PHYSICS REFERENCE BLOG

Friday, August 21, 2015

Dynamics | 9702 Physics Summary Notes

  • 4. Dynamics | 9702 Physics Summary Notes



4.1 Newton’s Laws of Motion

·  First law: if a body is at rest it remains at rest or if it is in motion it moves with a uniform velocity until it is acted on by resultant force or torque
·  Second law: the rate of change of momentum of a body is proportional to the resultant force and occurs in the direction of force; F=ma
·  Third law: if a body A exerts a force on a body B, then body B exerts an equal but opposite force on body A, forming an action-reaction pair


4.2 Mass and Weight

Mass
Weight
·  Measured in kilograms
·  Scalar quantity
·  Constant throughout the universe
·  Measured in Newtons
·  Vector quantity
·  Not constant
·  W=mg
·  Mass: is a measure of the amount of matter in a body, & is the property of a body which resists change in motion.
·  Weight: is the force of gravitational attraction (exerted by the Earth) on a body.


4.3 Momentum

· Linear momentum: product of mass and velocity
p = mv
· Force: rate of change of momentum
F = (mv - mu) / t
· Principle of conservation of linear momentum: when bodies in a system interact, total momentum remains constant provided no external force acts on the system.
mAuA + mBuB = mAvA + mBvB


4.4 Elastic Collisions

· Total momentum conserved
· Total kinetic energy is conserved
Example: Two identical spheres collide elastically. Initially, X is moving with speed v and Y is stationary. What happens after the collision? 

X stops and Y moves with speed v
Relative velocity before collision = Relative velocity after collision

uA - uB = vB - vA




4.5 Inelastic Collisions

relative speed of approach > relative speed of separation
o Total momentum is conserved
· Perfectly inelastic collision: only momentum is conserved, and the particles stick together after collision (i.e. move with the same velocity)
· In inelastic collisions, total energy is conserved but Ek may be converted into other forms of energy e.g. heat 





7 comments:

  1. i need help in this question
    Q: A stationary nucleus of mass 220u undergoes radioactive decay to produce a nucleus D of mass 216u and alpha particle of mass 4u
    the initial kinetic energy of the alpha particle is 1*10^-12(one times ten to the power of negative twelve)
    A) (i)state the law of conservation of linear momentum
    (ii) explain why the initial velocities of the nucleus D and the alpha particle must be in opposite directions
    B)(i) show that the initial speed of alpha particle in 1.7*10^7 m/s
    (ii)calculate the initial speed of nucleus D
    c) the range in air of the emitted alpha particle is 4.5 cm
    calculate the average deceleration of the alpha particle as it is stopped by the air

    ReplyDelete
  2. A stationary nucleus of mass 220u undergoes radioactive decay to produce a nucleus D of
    mass 216u and an α-particle of mass 4u

    The initial kinetic energy of the α-particle is 1.0 × 10^–12 J.
    (ii) Explain why the initial velocities of the nucleus D and the α-particle must be in
    opposite directions.
    (b) (i) Show that the initial speed of the α-particle is 1.7 × 10^7 m/s.
    (ii) Calculate the initial speed of nucleus D.
    (c)The range in air of the emitted α-particle is 4.5 cm.
    Calculate the average deceleration of the α-particle as it is stopped by the air.

    ReplyDelete
    Replies
    1. Check solution 1098 at
      http://physics-ref.blogspot.com/2016/02/physics-9702-doubts-help-page-234.html

      Delete
    2. sreenshot the question and send to the mail provided at
      http://physics-ref.blogspot.com/2018/12/how-do-you-want-us-to-proceed-your.html

      comment here when the mail has already been sent

      Delete
  3. need help in 2018 march papers theory

    ReplyDelete

If it's a past exam question, do not include links to the paper. Only the reference.
Comments will only be published after moderation

Currently Viewing: Physics Reference | Dynamics | 9702 Physics Summary Notes