Exam-style question
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A car accelerates from rest to a speed of 25 m/s. If the mass of the car is 800 kg, calculate the kinetic energy of the car at this speed.
- A.250,000 J
- B.200,000 J
- C.100,000 J
- D.50,000 J
Model answer
What a good answer should say
- 200,000 J
Explanation
Why this works
The kinetic energy (Ek) is calculated using the formula Ek = 0.5 x m x v^2. Substituting the values: Ek = 0.5 x 800 kg x (25 m/s)^2 = 0.5 x 800 x 625 = 200,000 J.
Therefore, the kinetic energy of the car is 200,000 J.
Common mistake
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