Question

2. A car starts from rest and accelerates uniformly to

reach a speed of 21 m/s in 7.0 s. What was the speed of
the object after 2.0 seconds?​

Answer 1

speed of object after 2 seconds will be 6 ms⁻¹

Step-by-step explanation:

Initial velocity = 0

Final Velocity = 21 m/s

Time = 7 sec

We need to find speed of object after 2.0 seconds.

First we will find acceleration using formula:
`Accelaration=(change \ in \ velocity)/(change \ in \ time)`

Putting values:

`Accelaration=(Change \ in \ velocity)/(Change \ in \ time)\\Accelaration=(21-0)/(7)\\Accelaration=(21)/(7)\\Accelaration= 3 \ ms^(-2)`

Now finding speed of object after 2 seconds

The formula used will be:
`Speed(v) = a* t+v_0`

Putting values of a= 3m/s², t=2 sec and v₀=0 (at rest)

`Speed(v) = a* t+v_0\\Speed(v) = 3* 2+0\\Speed(v) =6\ ms^(-1)`

So, speed of object after 2 seconds will be 6 ms⁻¹