A motorist accelerates from rest to a velocity of $90 k m h r^{- 1}$ in $15$ seconds. What is the average acceleration of the car?

1.67 m s^{- 2}

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16.7 m s^{- 2}

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15 m s^{- 2}

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1.5 m s^{- 2}

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Solution

The correct option is A $1.67 m s^{- 2}$
Given:
Initial velocity $= 0 k m h r^{- 1} = 0 m s^{- 1}$ as he starts from rest.
Final velocity =
$90 k m h r^{- 1} = \frac{90 \times 5}{18} = 25 m s^{- 1}$
Acceleration is defined as the rate of change of velocity.
$a = \frac{F i n a l v e l o c i t y - I n i t i a l v e l o c i t y}{t i m e}$
$a = \frac{25 - 0}{15} = 1.67 m s^{- 2}$
Hence, the average acceleration of the car is $1.67 m s^{- 2}$

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