Question

a cars velocity increases from 36/km/h to 72 km/h . the car wieghs 1400kg .
calculate the work done by engine.​

Answer 1

Given

• Initial Velocity = 36 km/g
• Final Velocity = 72 km/h
• Mass = 1400 kg

To Find

• Work done by the engine

Solution

● Work done = Change in Kinetic Energy

● Change in Kinetic energy = Initial Ke - Final Ke

✭ Velocities of the car :

→ Initial Velocity = 36 × 5/18 = 10 m/s

→ Final Velocity = 72 × 5/18 = 20 m/s

✭ Initial Kinetic Energy :

→ Kᵢ = ½mu²

→ Kᵢ = ½ × 1400 × 36²

→ Kᵢ = 700 × 1296

→ Kᵢ = 907200 J

✭ Final Kinetic Energy

→ Kբ = ½mv²

→ Kբ = ½ × 1400 × 72²

→ Kբ = 700 × 5184

→ Kբ = 3628800 J

━━━━━━━━━━━━━━━━

✭ Work done by the engine :

→ Work = Kբ - Kᵢ

→ Work = 3628800 - 907200

→ Work = 2721600 J

→ Work = 2721.6 KJ

Answer 2

Answer:

Given :-

• Initial velocity = 36 km/h × 5/18 = 10 m/s
• Final velocity= 72 × 5/18 = 20 m/s
• Mass = 1400 kg

To Find :-

Work done

Solution :-

Work done = Final kinetic energy - Initial kinetic energy

Let's find initial kinetic energy

KEi = ½mu²

KEi = ½ × 1400 × 36²

KEi = 700 × 1296

KEi = 907200 J

Let's find final kinetic energy

KEf = ½mv²

KEf = ½ × 1400 × 72²

KEf = 1 × 700 × 5184

KEf = 3628800 J

Now,

Let's find work done

Work done = 3628800 - 907200

Work done = 2,721,600

Work done = 27,216 Kj