Question

a car is moving with initial velocity 20m/sec .car stopped after 5sec by application of the break. what is the acceleration of the car

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Answer 1

Answer: -4

Explanation:

Initial velocity u=20

Time taken to stop =5

Final velocity=0 since it stopped

Therefore v-u/t=a

(0-20)/5

=>a=-4m/s^-2

Note acceleration is-4 but deceleration is 4

Answer 2

a= - $4 m/s^2$

Explanation:

Given,Initial velocity(u) = 20 m/sec

         Time = 5 sec.

         Final velocity(v) = 0 m/s

We know that,

v = u +at

v-u = at

$\frac{v - u}{t} = a$

$\frac {0-20}{5} = a$

a= - $4 m/s^2$

Here negative value of acceleration shows the case of deceleration.