A Racing Car's Braking Action?

📌 CONCEPT: Newton's laws of motion, particularly the second law, help in understanding the braking action of the car by explaining the relationship between the force applied by the brakes and the resulting acceleration of the car.

📐 RULE / FORMULA: According to Newton's second law, F = ma, where F is the net force applied, m is the mass of the object, and a is its acceleration.

💡 WORKED EXAMPLE: Given that the car's mass (m) is 1500 kg and it comes to rest in 5 seconds, we can calculate its initial acceleration (a) using the formula v = u + at, where v = 0 (final velocity), u = 80 m/s (initial velocity), and t = 5 s. Rearranging the formula to solve for 'a', we get a = (v - u) / t = (0 - 80) / 5 = -16 m/s². Now, using F = ma, we can find the average force applied by the brakes (F) as F = 1500 * -16 = -24000 N, which is a magnitude of 24000 N.

⚠️ COMMON MISTAKE: Students often forget to consider the negative sign of acceleration when calculating the average force applied by the brakes, which can lead to incorrect results.