Question Detail
Question
A car of mass 1000kg moving at 100km/h comes to a stop in 50m. What is the magnitude of the force applied by the brakes?
Correct Answer
Option A is the correct answer.
Detailed Explanation
Convert 100 km/h to m/s: 100 × (1000/3600) = 27.78 m/s. Using v² = u² + 2as, 0 = (27.78)² + 2a(50). So a = -(27.78)²/(100) = -771.6/100 = -7.716 m/s². Force F = ma = 1000 × 7.716 = 7716 N ≈ 7720 N.
Hint
Use equations of motion to find acceleration, then F = ma.