Anonymous
Anonymous asked in Science & MathematicsPhysics · 1 month ago

A car accelerates from rest at 2 m/s² for 5 seconds, travels at constant speed for 10 seconds and....?

Cont...

decelerates to rest at 2 m/s². Calculate the distance travelled by the car.

2 Answers

Relevance
  • 1 month ago
    Favorite Answer

    Let's divide the distances part by part

    d1 = initial velocity x time + 1/2 x acceleration x time^2

         = 0 x 5 + 1/2 x 2 x 5^2

         = 1 x 25

         25 m

    velocity  = initial velocity + acceleration x time

    d2 = velocity x  time

         = (initial velocity + acceleration x time) x  time

         =  0 + 2 x 5 x 10

         =10x10

         = 100m

    deceleration = (initial velocity - final velocity) / time

    2 = (10-0)/time

    time = 10/2 = 5s

    d3 = (initial velocity + final velocity)/2 x time

         = (10 + 0)/2 x 5

          = 10/2 x 5

          = 5 x 5

          = 25m

    lets add up the distances

    d1 + d2 + d3

    =25 + 100 + 25

    = 150 m (Answer)

    • Jj1 month agoReport

      Supposedly your answer is 150
      100+25+25

    • Commenter avatarLogin to reply the answers
  • 1 month ago

    Answer to this problem = 150 m

    Time-Velocity Diagram of the movement is as follows. 

    From A to B, it accelerates @ 2 m/s²

    Hence Tan θ = 2 m/ s² = BE/AE. But AE = 5 second

    Hence BE = 10 m/s

    From B to C it moves with a constant velocity = BE = 10 m/s

    From C to D it moves with a retardation of 2 m/ s² 

    Hence slope of AB and CD are numerically equal to each other.

    Hence Total distance ( D ) traveled = Area of the Trapezium ABCDA 

    => D =  (1/2) ( AD + BC)*(BE)

    D = (1/2) (20+10)*10 = 150 m ……………….. Answer

    Attachment image
    • ...Show all comments
    • Jj1 month agoReport

      Thank you sir. I solved it and got the same answer as yours. I got confused at first because the key answer is 345 m, so maybe there's a mistake in the questionnaire.

    • Commenter avatarLogin to reply the answers
Still have questions? Get your answers by asking now.