motion

• What is the difference between speed and velocity?

  Speed is scalar; velocity is vector.
• How is instantaneous velocity found from a displacement-time graph?

  By calculating the gradient at a specific point.
• What is the equation for acceleration?

  $a =$$\frac{\Delta v}{\Delta t}$
• What are the four equations of motion for constant acceleration?

  1. $v =$$u +$$at$
  2. $s =$$ut +$$\frac{1}{2}at^2$
  3. $v^2 =$$u^2 +$$2as$
  4. $s =$$\frac{1}{2}(u + v)t$
• What assumptions are made in projectile motion problems?

  No air resistance; motions are independent.
• How does braking distance relate to speed?

  It is proportional to the square of speed.
• What factors affect a driver's thinking distance?

  • Reaction time
  • Alertness
  • Distractions
  • Alcohol
  • Drugs
• How can the value of g be experimentally determined?

  Using a trapdoor and electromagnet setup.
• What is the equation for force according to Newton's Second Law?

  $F =$$ma$
• What is the formula for weight?

  $W =$$mg$
• What is terminal velocity?

  Constant speed when drag equals weight.
• Name three factors that affect drag.

  • Speed
  • Cross-sectional area
  • Fluid density
• How do you calculate the moment of a force?

  $M =$$F \times d$
• What are the two conditions for equilibrium?

  Net force = 0 and net moment = 0.
• State the principle of moments.

  Total clockwise moment equals total anticlockwise moment.
• What is Archimedes' principle?

  Upthrust equals weight of fluid displaced.
• How is pressure in a fluid calculated?

  $p =$$h \rho g$
• What experiment can find the centre of mass of a flat object?

  Suspend it and draw vertical lines.
• What is the formula for work done at an angle?

  $W =$$Fd \cos \theta$
• What is the equation for kinetic energy?

  $E_k =$$\frac{1}{2}mv^2$
• How do you calculate gravitational potential energy?

  $E_p =$$mgh$
• State the principle of conservation of energy.

  Energy cannot be created or destroyed.
• How is power defined?

  Rate of energy transfer or work done.
• What is the unit of power?

  Watts (W), equal to Joules per second.
• How is efficiency calculated?

  $\frac{\text{Useful Output Energy}}{\text{Total Input Energy}} \times 100\%$
• In which scenario is $P =$$Fv$ used?


  When moving at constant velocity against resistive forces.
• What is Hooke's Law?

  $F =$$kx$, force is proportional to extension.
• What is the unit of the spring constant?

  Newton per metre (Nm\(^{-1}\)).
• How can you identify the elastic limit on a force-extension graph?

  It's where the graph stops being linear.
• What does the area under a force-extension graph represent?

  Elastic potential energy stored in the material.
• What is the difference between stress and strain?

  Stress = force per unit area; strain = extension per original length.
• What is the formula for the Young modulus?

  $E =$$\frac{\sigma}{\varepsilon}$
• What is hysteresis in rubber materials?

  Energy loss shown as a loop on the graph.
• How do you determine the Young modulus from an experiment?

  Measure diameter, length, force, and extension.
• What is the difference between brittle and ductile materials?

  Brittle breaks with little deformation; ductile stretches significantly.
• What happens at the yield point of a material?

  Rapid increase in extension with little increase in force.
• State Newton's First Law of Motion.

  An object remains at rest or moves uniformly unless acted on.
• What is Newton's Second Law in terms of momentum?

  $F =$$\frac{\Delta p}{\Delta t}$
• What is Newton's Third Law?

  For every action, there is an equal and opposite reaction.
• What is the definition of linear momentum?

  $p =$$mv$, product of mass and velocity.