Engineering - unit 2

• Finish the sentence

  • kilogram is a unit of mass
  • metre is a unit of length
  • second is a unit of time
  • ampere is a unit of electrical current
  • kelvin is a unit of thermodynamic temperature
  • mole is a unit of amount of substance
  • candela is a unit of luminous intensity
• Finish the sentence

  • mega M is 10^6
  • hecto h is 10^2
  • deca d is 10^1
  • centi c is 10^-2
  • milli m is 10^-3
  • micro u is 10^-6
  • nano n is 10^-9
• What is Accuracy

  how close the measured value is to the actual true value
• What is Precision

  how close the measured values are to each other
• why do we calibrate an instrument

  to minimise any measurement uncertainty by ensuring the accuracy
• What is Accuracy Class

  the percantage of the inherent error of a measuring device with respect to full scale deflection
• what is intrinsic error

  error of a measuring instrument determined under reference conditions
• what is uncertainty

  measures within a range and either side is accepted
• true value

  value that would be the perfect measurement
• what is error

  differnece between the measured value and the true value of the thing being measured
• What is the formula for Standard error

  SE = S/√ n
• what is a scalar quantitiy

  only measures magnitude
• what is a vector quantity

  measures magnitude and direction
• what is speed

  rate at which the object covers distance - no direction
• what is displacement

  overall change in position of an object - with direction
• what is velocity

  speed with direction or how quickly displacement changes over time
• what is acceleration

  how quickly velocity changes over time - with direction
• what is electrical current

  a rate of flow of charged particles
• What type of graph relates position to time?

  Displacement-time graph
• How can average variable velocity be determined from a displacement-time graph?

  From the gradient of the graph
• What does a positive slope on a displacement-time graph indicate?

  Motion moves away from the origin
• What does a negative slope on a displacement-time graph indicate?

  Motion moves towards the origin
• What does a steeper line on a displacement-time graph indicate?

  constant velocity
• What does a tangent sloping line on a displacement-time graph indicate?

  Accelerated motion
• What does the gradient of a displacement-time graph represent?

  constant Velocity
• How does acceleration appear on a displacement-time graph?

  As a constantly changing gradient
• What is the formula for velocity in terms of displacement and time?

  $v =$$\Delta x / \Delta t$
• How do you determine instantaneous velocity from a graph?

  By drawing a tangent and finding its gradient
• If the tangent at a specific point gives a gradient of 8, what is the instantaneous velocity?

  $8 \text{ ms}^{-1}$
• What do velocity-time graphs relate?

  Measured velocity of an object to time
• What does a positive slope on a velocity-time graph indicate?

  Velocity is increasing
• What does a negative slope on a velocity-time graph indicate?

  non uniform deceleration
• What does a steeper line on a velocity-time graph indicate?

  acceleration
• What does the formula for acceleration in terms of velocity and time represent?

  $a =$$\Delta v / \Delta t$
• What does the area under a velocity-time graph represent?

  Total displacement of an object
• What are the key points to note about displacement-time graphs?

  • Positive slope: moves away from origin
  • Negative slope: moves towards origin
  • Steep line: constant velocity
  • Tangent line: indicates accelerated motion
  • Straight line: indicates staitonary
• What are the key points to note about velocity-time graphs?

  • Positive slope: non uniform acceleration
  • Negative slope: non uniform deceleration
  • Steeper line: acceleration
  • Straight line: indictaes constant velocity
  • Gradient formula: $a =$$\Delta v / \Delta t$
• What are the methods to calculate displacement from a velocity-time graph?

  • Calculate area under the graph
• Draw a displacement time graph


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• Draw a Velocity time graph 


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