Question

starting from rest velocity is 5 m/s in 20 sec after some time the velocity decreases to 3 m/s in next 6 s calculate the acceleration in both the cases​

Answer 1

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In first case

Initial velocity ,u = 0m/s

Final velocity ,v = 5m/s

Time taken ,t = 20s

As we know that acceleration is defined as the rate of change in velocity.

a = v-u/t

where,

v is the final velocity

a is the acceleration

u is the initial velocity

t is the time taken

Substitute the value we get

:\implies:⟹ a = 5-0/20

:\implies:⟹ a = 5/20

:\implies:⟹ a = 1/4

:\implies:⟹ a = 0.25m/s²

Hence, the acceleration in 1st case is 0.25m/s²

__________________________

Now, calculating the acceleration in the 2nd case

Initial velocity ,u =5m/s

Final velocity ,v = 3m/s

Time taken ,t = 6

:\implies:⟹ a = v-u/t

:\implies:⟹ a = 3-5/6

:\implies:⟹ a = -2/6

:\implies:⟹ a = -1/3

:\implies:⟹ a = -0.33 m/s²

Here, negative sign show retardation

Hence, the acceleration in 2nd case is 0.33m/s²