Physics - Topic 2 - Motion and Forces

• What is the definition of a vector?

  A vector has magnitude and direction.
• What is the definition of a scalar?

  A scalar has just magnitude.
• Why can scalars generally not be negative?

  Scalars represent quantities that do not have direction, so they cannot be negative.
• Give an example of a scalar quantity.

  Speed is a scalar.
• Give an example of a vector quantity.

  Velocity is a vector.
• What is the scalar quantity for distance traveled?

  Distance is a scalar.
• What is the vector quantity for distance traveled?

  Displacement is a vector.
• What is the scalar quantity for time?

  Time is a scalar.
• What is the vector quantity for acceleration?

  Acceleration is a vector.
• What is the vector quantity for force?

  Force is a vector.
• What is the scalar quantity for mass?

  Mass is a scalar.
• What is the vector quantity for momentum?

  Momentum is a vector.
• What is the scalar quantity for energy?

  Energy is a scalar.
• In the example of a ball thrown off a cliff, what is the displacement at the height of the cliff?

  The displacement is 0 at the height of the cliff.
• How can you set the "0" point of a vector in long answer questions?

  You can set zero to be at the bottom of the cliff, for example.
• What distinguishes speed from velocity?

  Speed is only velocity when given a direction.
• What does the gradient of a displacement-time graph represent?

  The gradient represents velocity.

  
• What does a sharper gradient on a displacement-time graph indicate?

  A sharper gradient means faster speed.
• What does a negative gradient on a displacement-time graph indicate?

  A negative gradient indicates returning back to the starting point.
• What does a horizontal line on a displacement-time graph indicate?

  A horizontal line indicates the object is stationary.
• What does 0 distance mean on a displacement-time graph?

  0 distance means that the object is back to the starting point.

  
• What does the area under the line in a displacement-time graph represent?

  The area under the line represents nothing.
• What does a curved line on a displacement-time graph indicate?

  A curved line indicates that the velocity is changing (acceleration).
• What does the gradient of a velocity-time graph represent?

  The gradient represents acceleration.

  
• What does a sharper gradient on a velocity-time graph indicate?

  A sharper gradient means greater acceleration.
• What does a negative gradient on a velocity-time graph indicate?

  A negative gradient indicates deceleration.

  
• What does a horizontal line on a velocity-time graph indicate?

  A horizontal line indicates constant speed.
• What does 0 velocity mean on a velocity-time graph?

  0 velocity means that the object is stationary.
• What does the area under the line in a velocity-time graph represent?

  The area under the line represents distance traveled.
• What does a curved line on a velocity-time graph indicate?

  A curved line indicates that the acceleration is changing.
• What is average speed used for?

  Average speed is used when the speed changes during the motion.
• How do you calculate average speed?

  Use overall distances and timings to work out average speed.
• What is the formula for speed?

  Speed = distance / time.
• How do you measure speed for constant speeds?

  Measure distance traveled and use a stopwatch for time taken.
• How do you measure average speed?

  Work out total distance traveled and find the time taken for the whole journey.
• How do light gates measure speed?

  Light gates measure the time taken for an object to pass between them.
• Why are light gates more accurate than stopwatches?

  Light gates remove reaction time and human error with a stopwatch.
• What is the typical speed of wind?

  5 − 7 m/s.
• What is the typical speed of sound?

  340 m/s.
• What is the typical speed of walking?

  5 km/h = ~ 1.4 m/s.