Weighing Scale
Make your own spring scale!
What You Need
Materials per student
- Small paper cup
- Rubber band
- String (1/2 metre)
- Paper clip
- Large craft stick
- Tape
- Scissors
- Pencil or pen
- Ruler
Guide:
Safety Notes
Ensure you are familiar with Let's Talk Science's precautions with respect to safe virtual delivery to youth.
What To Do
To make a spring scale, each student will:
- Carefully poke three evenly spaced holes along the rim of the paper cup with a pencil or pen.
- Cut three pieces of string that are around 15 cm (make sure all three pieces are the same size).
- Thread each string through a hole and tie a small knot at each end.
- Knot the three strings together at the top. This is the string handle.
- Loop a paper clip through the string handle.
- Loop the other end of the paper clip through a rubber band.
- Loop the other end of the rubber band onto the craft stick.
- Tape the stick to a tabletop or flat surface workspace. This is the balance.
- Using the piece of paper, create a 'scale' by writing in horizontal lines every centimetre and number the lines in order.
- Place the piece of paper behind the balance and ensure that the first line is at the bottom of the paper clip.
Students can place various objects in the cup and see how far down the scale they go.
Discovery
When an object is placed on the scale, the force of gravity pulls down on the balance and stretches along the scale. The scale measures the mass of the object. If the rubber band is stretched very far, the object is heavier. If the rubber band is not stretched, the object is lighter than the balance.
What's Happening?
When an object is placed on the scale, the force of gravity pulls down on the balance and stretches along the scale. The scale measures the mass of the object. If the rubber band is stretched very far, the object is heavier. If the rubber band is not stretched, the object is lighter than the balance.