Question

A car accelerates uniformly from rest and acquires a speed of 72km/h in 10sec find the acceleration and total distance travelled at 7th second.​

Answer 1

Given :-

• Initial velocity (u)= 0 m/s

Final velocity(v) = 72 km / hr

In order to convert km / he into m /s simply multiply by 5 /18

• Final velocity (v)= 72 x 5 / 18 = 4 x 5 = 20 m /s
• time taken(t) = 10 s

To find : -

• Acceleration(a )
• Distance traveled by the car in 7 th second (s)

Solution :-

As the car accelerates uniformly throughout it's motion  we can use the first kinematic equation to find the acceleration

⟹ v = u + at

On rearranging ,

⟹ a = v - u / t

⟹ a = 20 - 0 / 10

⟹ a = 20 / 10

⟹ a = 2 m/s²

The acceleration of the car is 2 m/s ²

The distance covered by the car in n th second is given by the formula ,

⟹ S = u + a /2 ( 2n-1 )

Now let's substitute the given values in the above equation ,

⟹ S = 0 + 2 /2 (2x7 -1)

⟹ S = 14 -1

⟹ S = 13 m

∴ Distance covered by the car in the 7 th second = 13 m

Answer 2

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