• The following equation of motion applies to objects moving with?uniform (constant) acceleration:

(final speed)²?= (initial speed)²?+ 2 × acceleration × distance moved

v²?= u²?+ 2as

• Where:
  • s?= distance moved in metres (m)
  • u?= initial speed in metres per second (m/s)
  • v?= final speed in metres per second (m/s)
  • a?= acceleration in metres per second squared (m/s²)

   

• This equation is used to calculate quantities such as?initial or final speed,?acceleration, or?distance moved?in cases where the?time taken?is?not known

Step 1: Identify and write down the equation to use

• • The question says that the car 'accelerates steadily' - so the equation for?uniform acceleration?can be used:

   

v²?= u²?+ 2 × a × s

Step 2: List the known quantities

• • Initial speed,?u?= 0 m/s (the car starts?from rest)
  • Final speed,?v?= 16 m/s
  • Acceleration,?a?= 2.5 m/s²
  • Distance moved,?s?= ? (this needs to be calculated)

   

Step 3: Substitute known quantities into the equation and simplify where possible

16²?= 0²?+ (2 × 2.5 ×?s)

• • This can be simplified to:

   

256 = 5 ×?s

Step 4: Rearrange the equation to work out the distance moved

s?= 256 ÷ 5

s?=?51.2 m

轉載自savemyexam