The impact velocity is 14.14 m s-1, derived from square root of two g h. Total kinetic energy equals 150 J, which divided by 3000 N resistive force gives a sand depression depth of 0.05 m.
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Reading Fig. 7.39, total energy is 30 J. At P, potential energy is 20 J giving velocity 6.32 m s-1. At Q, potential energy is 30 J giving velocity 0 m s-1. Point R cannot be reached since it requires ...
From Fig. 7.37, initial speed is 6 m s-1. The trapezoid area gives work done as 150 J, raising kinetic energy to 330 J and final speed to 8.12 m s-1. Acceleration is never negative since force stays positive.
For rotational balance, effort times effort arm equals load times load arm. Since the adult has twice the weight of the child, the child must sit at twice the distance from the fulcrum compared to the adult.
Chapter 7 “Work, Energy and Simple Machines” explains the concepts of work, energy and power. It describes different forms of energy and simple machines, helping me understand how machines make work easier in daily life.