Question

When the velocity of an object changes from 126km/h to 54km/h ,it produces an
acceleration of 4m/s2. The time taken to produce this acceleration will be –

Answer 1

Answer:

Ans:- The time taken for the acceleration is 45 second.

Explanation:

Initial velocity(u) = 126km/h

Final velocity(v) = 54km/h

Retardation(a) = 4m/s²

Time(t) = ? sec

According to formula,

a = ( v + u ) / t

=> t = ( v + u ) / a

=> t = ( 126 + 54 ) / 4

=> t = ( 180 ) / 4

=> t = 45

So time = t sec = 45 sec

Ans:- The time taken for the acceleration is 45 second.

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Answer 2

Explanation:

Given:

Initial velocity ($u$) = $126km/hr=35m/s$

Final velocity ($v$) = $54 km/hr=15m/s$

Acceleration ($a$) = $4m/s^{2}$

To find: Time taken ($t$) to produce this acceleration

Calculation:

Acceleration is negative because the object is actually decelerating from high velocity to low velocity. This is caused by negative acceleration or deceleration of the object.

From kinematics equation,

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

$t=\frac{v-u}{a} =\frac{15-35}{-4} =5s$

So, the time taken by the body to decelerate from $126 km/hr$ to $54 km/hr$ is $5s$.

Answer:

Time taken by the body to decelerate from $126 km/hr$ to $54 km/hr$ is $5s$.