An unsecured astronaut is floating in deep space. He switches on a hand held drill. The drill bit begins rotating clockwise with high angular velocity. Describe what happens to the astronaut- drill system and explain why.
An equal amount of rotational force is applied to both the drill head and the astronaut. Having a greater mass, the force has less noticeable effect on the astronaut, but he will rotate around the drill in the opposite direction.
This is defined by newtons 3rd law "for every action there is an equal and opposite reaction". On earth, this reaction has little effect. you might feel your hand twist slightly as you switch on the drill. In space, there is no resistance with which you can damp the rotational force imparted upon you, therefore you rotate.
When the astronaut switches on the handheld drill in deep space, some interesting phenomena occur due to conservation of angular momentum. The astronaut-drill system consists of the astronaut and the drill, and they both initially have zero angular momentum.
As the drill bit starts rotating clockwise with high angular velocity, its angular momentum increases. According to the law of conservation of angular momentum, any change in the system's angular momentum must be compensated for elsewhere in the system. In this case, due to the absence of external torques acting on the system, the overall angular momentum of the system must remain constant.
To counterbalance the increase in angular momentum caused by the rotating drill bit, an equal and opposite change in angular momentum occurs elsewhere in the system. The astronaut experiences an equal but opposite change in angular momentum to maintain the system's overall angular momentum at zero.
As a result, the astronaut will begin to rotate in the opposite direction, counterclockwise. This is commonly referred to as the "reaction" or "counter-rotation" effect. The magnitude of the astronaut's rotational speed will depend on how the mass is distributed within the astronaut and the drill system. The moment of inertia, which depends on the distribution of mass and the distance from the axis of rotation, plays a role in determining the resulting angular velocity of the astronaut.
It's important to note that in reality, this scenario involving an unsecured astronaut would be extremely dangerous. In space, without any external forces acting on the system, the astronaut and the drill would indefinitely continue to rotate, making it difficult to stop or control the motion.