science
Grade-7
Easy

Question

A car moving at a velocity of 76 m/s decreases its velocity uniformly to 6 m/s in 10 s. Work out its acceleration with a proper sign.

  1. +7.5 m/s2
  2. + 5.5 m/s2
  3. -7 m/s2
  4. -5.5 m/s2

hintHint:

If the direction of acceleration is opposite to the direction of the velocity of an object then acceleration will be negative.

The correct answer is: -7 m/s2


    Given:
    Initial velocity (u) = 76ms-1
    Final velocity (v) = 6ms-1
    Time taken (t) = 10s
    Acceleration (a) = ?
    Formula used:
    v = u + at
    Solution: 
    6 = 76 + a cross times
 10
    a space equals space fraction numerator 6 space minus space 76 space over denominator 10 end fraction
    a space equals space fraction numerator negative 70 over denominator 10 space end fraction space equals space minus 7 m s to the power of negative 2 end exponent


    Answer: 
    Acceleration of car is -7ms-2 
     

    Negative acceleration is also known as deceleration.

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