The question
Name: ______________________ Date: ____________ Finding the mass of a cart (10 points)
Experimental setup
Finding the mass of a cart
Students want to find the mass M of a lab cart without using a balance. The cart sits on a level, low-friction track. A light string tied to the cart runs over a light, frictionless pulley at the end of the track to a hanger, on which they can place slotted masses. The total hanging mass m is known.
Their results (use g = 9.8 m/s²):
| Hanging mass m (kg) | Acceleration a (m/s²) |
|---|---|
| 0.050 | 0.58 |
| 0.100 | 1.08 |
| 0.150 | 1.55 |
| 0.200 | 1.97 |
| 0.250 | 2.33 |
(a) Describe a procedure the students could use to collect the acceleration data in the table. Include the equipment used to measure each quantity and a way to reduce experimental uncertainty. [3 points]
(b) For the cart-string-hanger system, Newton's second law gives a = mg/(M + m). Indicate what quantities the students should plot to obtain a straight line, and explain how they can use the line to find M. [2 points]
(c) Calculate the quantities you chose in part (b) and plot them on the grid. Label the axes with the quantities and units, choose a linear scale, and draw a best-fit line. [3 points]
(d) Calculate the mass M of the cart using your best-fit line. [2 points]