Weighing the cart with the Force probe
The Force probe can be used to measure the force of the Earth's gravity on masses. In other words, the Force probe can be used to measure the weight of masses. Connect the Force probe to your handheld computer. Refer to Technical Hints to see how to connect the cables.
Hold the Force probe so that you can hang things from the smaller eye bolt at the end of the arm. Set the force probe to zero in this position. Refer to Technical Hints to see how to set the Force probe to zero.
Try weighing something light, such as a pen hooked on with a paper clip. Expand the force scale so that you can see the change in weight. What is the smallest weight that you can measure?
Clear the graph and change the y-axis scale to read from 0 to 20N. Weigh something heavy, like a book. Note that the units are in newtons, not kilograms. What is the difference between newtons and kilograms? Explain your reasoning in Notes on your handheld computer.
Use a paper clip to make a hook so that you can hang the cart from the Force probe. It can be hooked to the bumper, around the propeller, or through the cardboard.
Clear the graph. Start recording with the software for force. Hang the cart from the Force probe for 10 seconds. Remove it and check that the force goes back to zero. Stop recording and save your data.
What was the average value for the weight of the cart? How steady was your reading? How much did it vary and why?
If you hang the cart with a rubber band and weigh it, will it be the same? Try it.
What variations do you get? Can you get a steady reading?
Calculate the mass, in kilograms, of your cart.
The conversion is mass (kg) = weight (newtons) / 9.8
What are the weight and the mass? Record your answers on Notes in your handheld computer.
How does this mass compare to the masses of the other carts.
