A steel wire is tied to two chairs and kept taut. 2 students sit one on each chair. A weight is attached to the long wire with help of a string and a pointer is attached to the weight to show the reading. What will happen to the arrow when candles are lit beneath the arrow?
When the candles are lit beneath the arrow, certain things will happen:
1. Heat transfer: The flames from the candles will heat the air around them, causing the air to expand and become less dense. This heated air will rise upwards due to convection currents.
2. Wire expansion: As the air around the candles heats up, it will also heat the steel wire. Steel expands when heated, so the wire will lengthen slightly.
3. Sagging wire: Due to the increased length of the wire, it will sag downwards between the two chairs. This sagging occurs because the weight of the wire is now less effectively supported by tension, allowing it to bend under its own weight.
4. Pointer movement: The weight attached to the wire will now be closer to the chairs, causing the pointer to move in the opposite direction. If the weight was initially hanging downwards, the pointer will move upwards, and if the weight was initially hanging upwards, the pointer will move downwards.
In summary, when the candles are lit beneath the arrow, the wire will expand and sag, causing the pointer to move accordingly.