Question

A racing car, initially at rest, picks up a velocity of 180 km h-1 in 5 s. Calculate : [4]

(i) final velocity in m s-1

(ii) average velocity

(iii) acceleration (iv) distance covered by the car.​

Answer 1

Given:-

→ Initial velocity of the car = 0

→ Final velocity of the car = 180 km h⁻¹

→ Time taken = 5s

To find:-

→ Final velocity in m s⁻¹

→ Average velocity

→ Acceleration

→ Distance covered by the car

Solution:-

Final velocity of the car in m s⁻¹ :-

=> 1km h⁻¹ = 5/18 m s⁻¹

=> 180 km h⁻¹ = 5/18 × 180 m s⁻¹

=> 50 m s⁻¹

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When a body is moving with uniform acceleration, then average velocity is given by :-

=> Vₐᵥ = u + v/2

=> Vₐᵥ = 0 + 50/2

=> Vₐᵥ = 25 m s⁻¹

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Now,let's calculate the acceleration of the car by using the 1st equation of motion :-

=> v = u + at

=> 50 = 0 + a(5)

=> 50 = 5a

=> a = 50/5

=> a = 10 m s⁻²

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Finally let's calculate the distance covered by the car by using the 2nd equation of motion :-

=> s = ut + ½at²

=> s = 0(5) + ½(10)(5)²

=> s = 0 + 5(25)

=> s = 125m

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Thus :-

• Final velocity in m s⁻¹ is 50 m s⁻¹ .

• Average velocity is 25 m s⁻¹ .

• Acceleration is 10 m s⁻² .

• Distance covered by the car is 125m .