Question

10. A bus decreases its speed from 80 km/h to
60 km/h in 5 s. Find the acceleration of the
bus.​

Answer 1

Answer:

-4

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Explanation:

$\frac{(60-80)}{5}$

$\frac{-20}{5}$

$\frac{-4}{1}$

$-4$

Answer 2

The acceleration of bus is $\dfrac{-50}{9} m/s^2$.

Explanation:

• Since, bus is going with the constant velocity of 80 Kmph. We assume, this is initial velocity.

• But, We are asked that the bus is slowed down to speed 60 kmph. We assume that it is final speed.  

• In this case, we can see that both velocities are constant. So Newton's law is applicable .

• Therefore, we write as;

        u = 80 kmph, v = 60 kmph, t = 5 sec , a = ?

It means, we should apply.

• v = u +at

We can covert the kmph in mps, by multiplying the number by 5/18.

Now, u = 900/18 mps, v = 50/3 mps, t = 5 seconds

     Put the values in  v = u + at.

• $\dfrac{50}{3} = \dfrac{900}{18} + a\times 5$

By solving it, we get;

• a = $\dfrac{-50}{9} m/s^2$

Thus, the acceleration of bus is $\dfrac{-50}{9} m/s^2$.