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An electric car is travelling at a speed of 16.0 m/s - Edexcel - GCSE Physics Combined Science - Question 5 - 2023 - Paper 2

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An electric car is travelling at a speed of 16.0 m/s. The total mass of the car is 1200 kg. (i) Calculate the kinetic energy, in kJ, of the car. (ii) On a journey... show full transcript

Worked Solution & Example Answer:An electric car is travelling at a speed of 16.0 m/s - Edexcel - GCSE Physics Combined Science - Question 5 - 2023 - Paper 2

Step 1

Calculate the kinetic energy, in kJ, of the car.

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Answer

To calculate the kinetic energy, we can use the formula:

KE=12mv2KE = \frac{1}{2} mv^2

where:

  • mm is the mass of the car (1200 kg)
  • vv is the speed (16.0 m/s)

Substituting the values:

KE=12×1200×(16.0)2KE = \frac{1}{2} \times 1200 \times (16.0)^2

Calculating:

KE=600×256=153600JKE = 600 \times 256 = 153600 \, \text{J}

To convert to kilojoules, we divide by 1000:

KE=153.6kJKE = 153.6 \, \text{kJ}

Thus, the kinetic energy of the car is approximately 150 kJ.

Step 2

Calculate the time taken for the battery to become discharged on this journey.

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Answer

To find the time taken for the battery to discharge, we can use the formula:

t=EPt = \frac{E}{P}

where:

  • EE is the energy transferred (126 MJ = 126 \times 10^6 , \text{J})
  • PP is the power rate (17.5 kW = 17500 , \text{W})

Substituting the values into the formula:

t=126×10617500t = \frac{126 \times 10^6}{17500}

Calculating:

t7200st \approx 7200 \, \text{s}

To convert seconds to hours:

t72003600=2hourst \approx \frac{7200}{3600} = 2 \, \text{hours}

Thus, the time taken for the battery to become discharged is 2 hours.

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