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Q2.14: NCERT Physics - Part 1 MOTION IN A STRAIGHT LINE 2.14 Solution: A police van moving on a highway with a speed of 30 km h�1…
⚠️ Common Exam Traps & Conceptual Pitfalls
Students often treat the bullet's muzzle speed (150 m s⁻¹) as its speed relative to the ground, forgetting to add the van’s 30 km h⁻¹ (≈8.33 m s⁻¹). Convert all speeds to the same units, add the van’s velocity to the muzzle speed, then subtract the thief’s car speed to obtain the damaging relative speed.
A police van moving on a highway with a speed of 30 km h�1 fires a bullet at a thief's car speeding away in the same direction with a speed of 192 km h�1. If the muzzle speed of the bullet is 150 m s�1, with what speed does the bullet hit the thief's car? (Note: Obtain that speed which is relevant for damaging the thief's car)
Step-by-Step Verified Solution
**Answer:** 105 m/s.
**Step-by-Step Explanation:**
Police van speed = 30 km/h = 8.33 m/s. Thief car speed = 192 km/h = 53.33 m/s.
Bullet speed relative to ground = 8.33 + 150 = 158.33 m/s.
Relative speed of bullet with respect to thief car = 158.33 - 53.33 = 105 m/s.
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