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.
Discussion Forum Latest Questions
From Fig. 6.41, the slope of the velocity-time line gives an acceleration of 2.5 m s-2. Multiplying this acceleration by the object mass of 10 kg gives a constant acting force of 25 N.
Option (iv) is correct because according to Newton’s third law of motion, whenever two objects interact during a collision, they exert equal and opposite forces on each other regardless of differences in their masses.
A cushioned landing mat increases the impact time during which the athlete’s downward velocity reduces to zero. According to Newton’s second law, extending the duration reduces acceleration, thereby significantly reducing the impact force and preventing injury.
Option (i) is correct because block P experiences an unbalanced net force of 1 N towards the right, while block Q moves at constant velocity, meaning the net external force acting upon Q is zero.