Converting 108 km h-1 gives 30 m s-1. The change in momentum is 0.4 kg multiplied by 30 m s-1, which equals 12 kg m s-1. Dividing by 800 N force gives 0.015 seconds contact time.
An ace footballer converted a penalty shot by kicking the football with a speed of 108 km h-1. The estimated force they imparted was 800 N. The mass of the football was 0.4 kg. Calculate the time of contact between their foot and the ball.
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The speed of 108 km h-1 converted to SI units equals 30 m s-1. The ball starts from rest, so its change in momentum equals mass times final velocity, which is 0.4 kg multiplied by 30 m s-1, equaling 12 kg m s-1. Since force equals change in momentum divided by time, dividing 12 by 800 N yields a contact time of 0.015 seconds.
For more NCERT Solutions of Class 9 Science Exploration Chapter 6 How Forces Affect Motion Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-6/