What is the force Suzie applies in holding the apple still?
The force Suzie applies in holding the apple still is equal to the weight of the apple, which is the gravitational force acting on it.
Understanding Suzie's Action
When Suzie holds the apple at rest in her outstretched hand, the force she applies is counteracting the force of gravity pulling the apple downward. According to Newton's second law of motion, the force (F) acting on an object is equal to the mass (m) of the object multiplied by its acceleration (a), or F = ma. Since the apple is at rest, its acceleration is zero. Therefore, the force Suzie applies (F) is equal to the weight of the apple, which is given by the equation: F = mg where (m) is the mass of the apple and (g) is the acceleration due to gravity (approximately 9.8 m/s² on the surface of the Earth).
Equilibrium of Forces
This equation implies that the force required to hold the apple still is directly proportional to its mass; a heavier apple would require a greater force to keep it at rest. In the case of Suzie holding the apple, the force she applies is essentially the gravitational force acting on the apple. Her hand exerts an upward force equal in magnitude but opposite in direction to the gravitational force pulling the apple downward. As long as these forces are balanced, the apple remains at rest in her hand. This equilibrium is a result of the fundamental principle of statics: when an object is at rest, the sum of the forces acting on it is zero. In mathematical terms, it can be expressed as: Σ F = 0.