forces , motion , formula

• Investigating whether a spring obeys Hooke's law


  1. Use the apparatus shown in the photograph

  2. Measure additional quantity
• Hooke's law


  Relationship between force and extension of a spring
• Investigating whether the spring obeys Hooke's law

  1. Measure force and extension

  2. Plot graph of force vs extension

  3. Check if graph is linear

  4. Determine spring constant from gradient
• Kinetic energy (KE)


  Energy of motion
• Kinetic energy, mass and velocity

  KE = 1/2 mv^2
• Passengers in lift below ground

  Gain gravitational potential energy
• Effect of sloping tunnel on train

  1. Brakes do less work to stop train going up slope

  2. Motor does more work to accelerate train going down slope
• Unbalanced force


  Net force acting on an object
• Unbalanced force, mass and acceleration

  F = ma
• Calculating initial acceleration of balloon

  Use F = ma with unbalanced force of 400 N and mass of 910 kg
• Change in acceleration during first few seconds of flight

  Acceleration decreases as upward force from burner decreases
• Velocity of the bus

  Speed of the bus
• Calculating distance travelled by bus


  Use v = d/t to solve for d
• Average velocity and distance

  Average velocity = total distance / total time
• Calculating total distance travelled


  1. Use v = u + at for first 30 s

  2. Use v^2 = u^2 + 2as for last 10 s

  3. Add the two distances
• Independent variable


  The variable that is changed or controlled in a scientific experiment to observe its effects on the dependent variable
• Dependent variable


  The variable that is observed or measured in a scientific experiment, and is 'dependent' on the independent variable
• Newton's first law states that if there are no external forces acting on an object, it will remain at rest or continue moving with constant velocity.